Term
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Definition
| THE ENVELOPE OF GASES THAT SURROUND A PLANET AND ARE HELD TO IT BY THE PLANET'S GRAVIATIONAL ATTRACTION. THE EARTH'S ATMOSPHERE IS MAINLY NITROGEN AND OXYGEN. |
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Term
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Definition
| (N2) A COLORLESS AND ODORLESS GAS THAT OCCUPIES ABOUT 78 PERCENT OF DRY AIR IN THE LOWER ATMOSPHERE. |
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Term
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Definition
| (O2) A COLORLESS, ODORLESS GAS THAT OCCUPIES AOBUT 21 PERCENT OF DRY AIR IN THE LOWER ATMOSPHERE. |
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Term
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Definition
| WATER IN A VAPOR (GASEOUS) FORM. ALSO CALLED MOISTURE. |
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Term
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Definition
| (CO2) A COLORLESS, ODORLESS GAS WHOSE CONCENTRATION IS ABOUT 0.038 PERCENT (380 PPM) IN A VOLUME OF AIR NEAR SEA LEVEL. IT IS A SELECTIVE ABSORBER OF INFRARED RADIATION AND, CONSEQUENTLY, IT IS IMPORTANT IN THE EARTH'S ATMOSPHERIC GREENHOUSE EFFECT. SOLID CO2 IS CALLED DRY ICE. |
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Term
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Definition
| (O3) AN ALMOST COLORLESS GASEOUS FORM OF OXYGEN WITH AN ODOR SIMILAR TO WEAK CHLORINE. THE HIGHEST NATURAL CONCENTRATION IS FOUND IN THE STRATOSPHERE WHERE IT IS KNOWN AS STRATOSPHERIC OZONE. IT ALSO FORMS IN POLLUTED AIR NEAR THE SURFACE WHERE IT IS THE MAIN INGREDIENT OF PHOTOCHEMICAL SMOG. HERE, IT IS CALLED TROPOSPHERIC OZONE. |
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Term
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Definition
| TINY SUSPENDED SOLID PARTICLES (DUST, SMOKE, ETC.) OR LIQUID DROPLETS THAT ENTER THE ATMOSPHERE FROM EITHER NATURAL OR HUMAN (ANTHROPOGENIC) SOURCES, SUCH AS THE BURNING OF FOSSIL FUELS. SULFUR-CONTAINING FOSSIL FUELS, SUCH AS COAL, PRODUCE SULFATE AEROSOLS. |
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Term
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Definition
| ANY GASEOUS, CHEMICAL, OR ORGANIC MATTER THAT CONTAMINATES THE ATMOSPHERE, SOIL, OR WATER. |
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Term
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Definition
| THE RELEASE OF GASES DISSOLVED IN HOT, MOLTEN ROCK. |
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Term
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Definition
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Term
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Definition
| (ATMOSPHERIC PRESSURE) THE PRESSURE EXERTED BY THE MASS OF AIR ABOVE A GIVEN POINT, USUALLY EXPRESSED IN MILLIBARS (MB), INCHES OF MERCURY (HG) OR IN HECTOPASCALS (HPA). |
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Term
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Definition
| THE RATE AT WHICH AN ATMOSPHERIC VARIABLE (USUALLY TEMPERATURE) DECREASES WITH HEIGHT. (SEE ENVIRONMENTAL LAPSE RATE.) |
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Term
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Definition
| AN INCREASE IN AIR TEMPERATURE WITH HEIGHT, OFTEN SIMPLY CALLED AN INVERSION. |
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Term
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Definition
| A BALLOON-BORNE INSTRUMENT THAT MEASURES AND TRANSMITS PRESSURE, TEMPERATURE, AND HUMIDITY TO A GROUND-BASED RECEIVING STATION. |
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Term
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Definition
| THE LAYER OF ATMOSPHERE EXTENDING FROM THE EARTH'S SURFACE UP TO THE TROPOPAUSE (ABOUT 10 KM ABOVE THE GROUND). |
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Term
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Definition
| THE LAYER OF ATMOSPHERE ABOVE THE TROPOSPHERE AND BELOW THE MESOSPHERE (BETWEEN 10 KM AND 50 KM), GENERALLY CHARACTERIZED BY AN INCREASE IN TEMPERATURE WITH HEIGHT. |
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Term
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Definition
| THE BOUNDARY BETWEEN THE TROPOSPHERE AND THE STRATOSPHERE. |
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Term
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Definition
| THE ATMOSPHERIC LAYER BETWEEN THE STRATOSPHERE AND THE THERMOSPHERE. LOCATED AT AN AVERAGE ELEVATION BETWEEN 50 AND 80 KM ABOVE THE EARTH'S SURFACE. |
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Term
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Definition
| THE ATMOSPHERIC LAYER ABOVE THE MESOSPHERE (ABOVE ABOUT 85 KM) WHERE THE TEMPERATURE INCREASES RAPIDLY WITH HEIGHT. |
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Term
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Definition
| AN ELECTRIFIED REGION OF THE UPPER ATMOSPHERE WHERE FAIRLY LARGE CONCENTRATIONS OF IONS AND FREE ELECTRONS EXIST. |
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Term
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Definition
| THE CONDITION OF THE ATMOSPHERE AT ANY PARTICULAR TIME AND PLACE. |
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Term
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Definition
| THE ELEMENTS OF AIR TEMPERATURE, AIR PRESSURE, HUMIDITY, CLOUDS, PRECIPITATION, VISIBILITY, AND WIND THAT DETERMINE THE PRESENT STATE OF THE ATMOSPHERE-THE WEATHER. |
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Term
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Definition
| THE ACCUMULATION OF DAILY AND SEASONAL WEATHER EVENTS OVER A LONG PERIOD OF TIME. |
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Term
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Definition
| THE STUDY OF THE ATMOSPHERE AND ATMOSPHERIC PHENOMENA AS WELL AS THE ATMOSPHERE'S INTERACTION WITH THE EARTH'S SURFACE, OCEANS, AND LIFE IN GENERAL. |
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Term
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Definition
| THE REGION OF THE WORLD TYPICALLY DESCRIBED AS BEING BETWEEN 30 DEGREES AND 50 DEGREES LATITUDE. |
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Term
| MIDDLE-LATITUDE CYCLONIC STORM |
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Definition
| SEE EXTRATROPICAL CYCLONE. |
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Term
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Definition
| A TROPICAL CYCLONE HAVING WINDS IN EXCESS OF 64 KNOTS (74 MI/HR). |
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Term
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Definition
| A LOCAL STORM PRODUCED BY CUMULONIMBUS CLOUDS. ALWAYS ACCOMPANIED BY LIGHTNING AND THUNDER. |
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Term
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Definition
| AN INTENSE, ROTATING COLUMN OF AIR THAT OFTEN PROTRUDES FROM A CUMULONIMBUS CLOUD IN THE SHAPE OF A FUNNEL OR A ROPE WHOSE CIRCULATION IS PRESENT ON THE GROUND. (SEE FUNNEL CLOUD.) |
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Term
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Definition
| AIR IN MOTION RELATIVE TO THE EARTH'S SURFACE. |
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Term
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Definition
| THE DIRECTION FROM WHICH THE WIND IS BLOWING. |
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Term
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Definition
| THE TRANSITION ZONE BETWEEN TWO DISTINCT AIR MASSES. |
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Term
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Definition
| THE ENERGY WITHIN A BODY THAT IS A RESULT OF ITS MOTION. |
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Term
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Definition
| THE DEGREE OF HOTNESS OR COLDNESS OF A SUBSTANCE AS MEASURED BY A THERMOMETER. IT IS ALSO A MEASURE OF THE AVERAGE SPEED OR KINETIC ENERGY OF THE ATOMS AND MOLECULES IN A SUBSTANCE. |
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Term
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Definition
| A TEMPERATURE READING OF -273 DEGREES C, -460 DEGREES F, OR 0 K. THEORETICALLY, THERE IS NO MOLECULAR MOTION AT THIS TEMPERATURE. |
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Term
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Definition
| A FORM OF ENERGY TRANSFERRED BETWEEN SYSTEMS BY VIRTURE OF THEIR TEMPERATURE DIFFERENCES. |
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Term
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Definition
| A TEMPERATURE SCALE WITH ZERO DEGREES EQUAL TO THE THEORETICAL TEMPERATURE AT WHICH ALL MOLECULAR MOTION CEASES. ALSO CALLED THE ABSOLUTE SCALE. THE UNITS ARE SOMETIMES CALLED "DEGREES KELVIN"; HOWEVER, THE CORRECT SI TERMINOLOGY IS "KELVINS," ABBREVIATED K. |
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Term
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Definition
| A TEMPERATURE SCALE WHERE 32 IS ASSIGNED TO THE TEMPERATURE AT WHICH WATER FREEZES AND 212 TO THE TEMPERATURE AT WHICH WATER BOILS (AT SEA LEVEL.) |
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Term
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Definition
| A TEMPERATURE SCALE WHERE ZERO IS ASSIGNED TO THE TEMPERATURE WHERE WATER FREEZES AND 100 TO THE TEMPERATURE WHERE WATER BOILS (AT SEA LEVEL). |
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Term
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Definition
| THE HEAT THAT IS EITHER RELEASED OR ABSORBED BYA UNIT MASS OF A SUBSTANCE WHEN IT UNDERGOES A CHANGE OF STATE, SUCH AS DURING EVAPORATION, CONDENSATION, OR SUBLIMATION. |
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Term
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Definition
| THE HEAT WE CAN FEEL AND MEASURE WITH A THERMOMETER. |
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Term
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Definition
| A SMALL, RISING PARCEL OF WARM AIR PRODUCED WHEN THE EARTH'S SURFACE IS HEATED UNEVENLY. |
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Term
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Definition
| THE HORIZONTAL TRANSFER OF ANY ATMOSPHERIC PROPERTY BY THE WIND. |
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Term
| RADIANT ENERGY (RADIATION) |
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Definition
| (RADIATION) ENERGY PROPOGATED IN THE FORM OF ELECTROMAGNETIC WAVES. THESE WAVES DO NOT NEED MOLECULES TO PROPGATE THEM, AND IN A VACUUM THEY TRAVEL AT NEARLY 300,000 KM PER SEC (186,000 MI PER SEC). |
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Term
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Definition
|
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Term
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Definition
| A UNIT OF LENGTH EQUAL TO ONE-MILLIONTH OF A METER. |
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Term
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Definition
| A DISCRETE UNIT OF ENERGY THAT CAN BE THOUGHT OF AS A PACKET OF ELECTROMAGNETIC RADIATION TRAVELING AT THE SPEED OF LIGHT. |
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Term
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Definition
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Term
| ULTRAVIOLET RADIATION (UV) |
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Definition
| ELECTROMAGNETIC RADIATION WITH WAVELENGTHS LONGER THAN X-RAYS BUT SHORTER THAN VISIBLE LIGHT. |
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Term
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Definition
| ELECTROMAGNETIC RADIATION WITH WAVELENGTHS BETWEEN ABOUT 0.7 AND 1000 MICROMETERS. THIS RADIATION IS LONGER THAN VISIBLE RADIATION BUT SHORTER THAN MICROWAVE RADIATION. |
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Term
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Definition
| A HYPOTHETICAL OBJECT THAT ABSORBS ALL OF THE RADIATION THAT STRIKES IT. IT ALSO EMITS RADIATION AT A MAXIMUM RATE FOR ITS GIVEN TEMPERATURE. |
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Term
| RADIATIVE EQUILIBRIUM TEMPERATURE |
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Definition
| THE TEMPERATURE ACHIEVED WHEN AN OBJECT, BEHAVING AS A BLACKBODY, IS ABSORBING AND EMITTING RADIATION AT EQUAL RATES. |
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Term
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Definition
| SUBSTANCES SUCH AS WATER VAPOR, CARBON DIOXIDE, CLOUDS, AND SNOW THAT ABSORB RADIATION ONLY AT PARTICULAR WAVELENGTHS. |
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Term
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Definition
| SEE ATMOSPHERIC GREENHOUSE EFFECT. |
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Term
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Definition
| THE WAVELENGTH RANGE BETWEEN 8 AND 11 MICROMETERS IN WHICH LITTLE ABSORPTION OF INFRARED RADIATION TAKES PLACE. |
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Term
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Definition
| THE RATE AT WHICH SOLAR ENERGY IS RECEIVED ON A SURFACE AT THE OUTER EDGE OF THE ATMOSPHERE PERPENDICULAR TO THE SUN'S RAYS WHEN THE EARTH IS AT A MEAN DISTANCE FROM THE SUN. THE VALUE OF THE SOLAR CONSTANT IS ABOUT TWO CALORIES PER SQUARE CENTIMETER PER MINUTE OR ABOUT 1376 W/M2 IN THE SI SYSTEM OF MEASUREMENT. |
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Term
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Definition
| THE PROCESS BY WHICH SMALL PARTICLES IN THE ATMOSPHERE DEFLECT RADIATION FROM ITS PATH INTO DIFFERENT DIRECTIONS. |
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Term
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Definition
|
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Term
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Definition
| THE PERCENT OF RADIATION RETURNING FROM A SURFACE COMPARED TO THAT WHICH STRIKES IT. |
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Term
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Definition
| GLOWING LIGHT DISPLAY IN THE NIGHT SKY CAUSED BY EXCITED GASES IN THE UPPER ATMOSPHERE GIVING OFF LIGHT. IN THE NORTHERN HEMISPHERE IT IS CALLED THE AURORA BOREALIS (NORTHERN LIGHTS); IN THE SOUTHERN HEMISPHERE, THE AURORA AUSTRALIS (SOUTHERN LIGHTS). |
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Term
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Definition
| APPROXIMATELY JUNE 21 IN THE NORTHERN HEMISPHERE WHEN THE SUN IS HIGHEST IN THE SKY AND DIRECTLY OVERHEAD AT LATITUDE 23 1/2 DEGREES N, THE TROPIC OF CANCER. |
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Term
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Definition
| THE EQUINOX AT WHICH THE SUN APPROACHES THE SOUTHERN HEMISPHERE AND PASSES DIRECTLY OVER THE EQUATOR. OCCURS AROUND SEPTEMBER 23. |
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Term
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Definition
| AN UNSEASONABLY WARM SPELL WITH CLEAR SKIES NEAR THE MIDDLE OF AUTUMN. USUALLY FOLLOWS A SUBSTANTIAL PERIOD OF COOL WEATHER. |
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Term
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Definition
| APPROXIMATELY DECEMBER 21 IN THE NORTHERN HEMISPHERE WHEN THE SUN IS LOWEST IN THE SKY AND DIRECTLY OVERHEAD AT LATITUDE 23 1/2 DEGREES S, THE TROPIC OF CAPRICORN. |
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Term
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Definition
| THE EQUINOX AT WHICH THE SUN APPROACHES THE NORTHERN HEMISPHERE AND PASSES DIRECTLY OVER THE EQUATOR. OCCURS AROUND MARCH 20. |
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Term
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Definition
| THE PROCESS BY WHICH THE EARTH'S SURFACE AND ADJACENT AIR COOL BY EMITTING INFRARED RADIATION. |
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Term
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Definition
| AN INCREASE IN TEMPERATURE WITH HEIGHT DUE TO RADIATIONAL COOLING OF THE EARTH'S SURFACE. ALSO CALLED A NOCTURNAL INVERSION. |
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Term
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Definition
| HORIZONTAL ZONES OF VEGETATION FOUND ALONG HILLSIDES THAT ARE PRIMARILY THE RESULT OF VERTICAL TEMPERATURE VARIATIONS. |
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Term
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Definition
| OIL HEATERS PLACED IN ORCHARDS THAT GENERATE HEAT AND PROMOTE CONVECTIVE CIRCULATIONS TO PROTECT FRUIT TREES FROM DAMAGING LOW TEMPERATURES. ALSO CALLED SMUDGE POTS. |
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Term
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Definition
| FANS PLACED IN ORCHARDS FOR THE PURPOSE OF MIXING COLD SURFACE AIR WITH WARMER AIR ABOVE. |
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Term
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Definition
| A CONDITION OCCURING OVER A WIDESPREAD AREA WHEN THE SURFACE AIR TEMPERATURE REMAINS BELOW FREEZING FOR A SUFFICIENT TIME TO DAMAGE CERTAIN AGRICULTURAL CROPS. A FREEZE MOST OFTEN OCCURS AS COLD AIR IS ADVECTED INTO A REGION, CAUSING FREEZING CONDITIONS TO EXIST IN A DEEP LAYER OF SURFACE AIR. ALSO CALLED ADVECTION FROST. |
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Term
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Definition
| THE MAIN FACTORS THAT CAUSE VARIATIONS IN TEMPERATURE FROM ONE PLACE TO ANOTHER. |
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Term
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Definition
| A LINE CONNECTING POINTS OF EQUAL TEMPERATURE. |
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Term
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Definition
| THE RATIO OF THE HEAT ABSORBED (OR RELEASED) BY THE UNIT MASS OF THE SYSTEM TO THE CORRESPONDING TEMPERATURE RISE (OR FALL). |
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Term
| DAILY (DIURNAL) RANGE OF TEMPERATURE |
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Definition
| THE DIFFERENCE BETWEEN THE MAXIMUM AND MINIMUM TEMPERATURES FOR ANY GIVEN DAY. |
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Term
| MEAN (AVERAGE) DAILY TEMPERATURE |
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Definition
| THE AVERAGE OF THE HIGHEST AND LOWEST TEMPERATURE FOR A 24-HOUR PERIOD. |
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Term
| ANNUAL RANGE OF TEMPERATURE |
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Definition
| THE DIFFERENCE BETWEEN THE WARMEST AND COLDEST MONTHS AT ANY GIVEN LOCATION. |
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Term
| MEAN (AVERAGE) ANNUAL TEMPERATURE |
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Definition
| THE AVERAGE TEMPERATURE AT ANY GIVEN LOCATION FOR THE ENTIRE YEAR. |
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Term
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Definition
| A FORM OF THE DEGREE-DAY USED AS AN INDEX FOR FUEL CONSUMPTION. |
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Term
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Definition
| A FORM OF DEGREE-DAY USED IN ESTIMATING THE AMOUNT OF ENERGY NECESSARY TO REDUCE THE EFFECTIVE TEMPERATURE OF WARM AIR. A COOLING DEGREE-DAY IS A DAY ON WHICH THE AVERAGE TEMPERATURE IS ONE DEGREE ABOVE A DESIRED BASE TEMPERATURE. |
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Term
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Definition
| A FORM OF THE DEGREE-DAY USED AS A GUIDE FOR CROP PLANTING AND FOR ESTIMATING CROP MATURITY DATES. |
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Term
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Definition
| THE SENSATION OF TEMPERATURE THAT THE HUMAN BODY FEELS IN CONTRAST TO THE ACTUAL TEMPERATURE OF THE ENVIRONMENT AS MEASURED WITH A THERMOMETER. |
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Term
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Definition
| THE COOLING EFFECT OF ANY COMBINATION OF TEMPERATURE AND WIN, EXPRESSED AS THE LOSS OF BODY HEAT. ALSO CALLED WIND-CHILL FACTOR. |
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Term
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Definition
| THE PARTIAL FREEZING OF EXPOSED PARTS OF THE BODY, CAUSING INJURY TO THE SKIN AND SOMETIMES TO DEEPER TISSUES. |
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Term
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Definition
THE DETERIORATION IN ONE'S MENTAL AND PHYSICAL CONDITION BROUGHT ON BY A RAPID LOWERING OF HUMAN BODY TEMPERATURE. |
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Term
| LIQUID-IN-GLASS THERMOMETER |
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Definition
|
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Term
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Definition
| A THERMOMETER WITH A SMALL CONSTRICTION JUST ABOVE THE BULB. IT IS DESIGNED TO MEASURE THE MAXIMUM AIR TEMPERATURE. |
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Term
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Definition
| A THERMOMETER DESIGNED TO MEASURE THE MINIMUM TEMPERATURE DURING A DESIRED TIME PERIOD. |
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Term
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Definition
| THERMOMETERS THAT USE ELEMENTS THAT CONVERT ENERGY FROM ONE FORM TO ANOTHER (TRANSDUCERS). COMMON ELECTRICAL THERMOMETERS INCLUDE THE ELECTRICAL RESISTANCE THERMOMETER, THERMOCOUPLE, AND THERMISTOR. |
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Term
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Definition
|
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Term
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Definition
| A TEMPERATURE-MEASURING DEVICE USUALLY CONSISTING OF TWO DISSIMILAR METALS THAT EXPAND AND CONTRACT DIFFERENTIALLY AS THE TEMPERATURE CAHNGES. |
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Term
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Definition
| AN INSTRUMENT THAT MEASURES AND RECORDS AIR TEMPERATURE. |
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Term
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Definition
| A BOXLIKE, OFTEN WOODEN, STRUCTURE DESIGNED TO PROTECT WEATHER INSTRUMENTS FROM DIRECT SUNSHINE AND PRECIPITATION. |
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Term
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Definition
| THE PROCESS BY WHICH A LIQUID CHANGES INTO A GAS. |
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Term
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Definition
| THE PROCESS BY WHICH WATER VAPOR BECOMES A LIQUID. |
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Term
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Definition
| ANY FORM OF WATER PARTICLES-LIQUID OR SOLID-THAT FALLS FROM THE ATMOSPHERE AND REACHES THE GROUND. |
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Term
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Definition
| A MODEL THAT ILLUSTRATES THE MOVEMENT AND EXCHANGE OF WATER AMONG THE EARTH, ATMOSPHERE, AND OCEANS. |
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Term
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Definition
| AN ATMOSPHERIC CONDITION WHEREBY THE LEVEL OF WATER VAPOR IS THE MAXIMUM POSSIBLE AT THE EXISTING TEMEPRATURE AND PRESSURE. |
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Term
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Definition
| ALSO CALLED CLOUD CONDENSATION NUCLEI. TINY PARTICLES UPON WHOSE SURFACES CONDENSATION OF WATER VAPOR BEGINS IN THE ATMOSPHERE. |
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Term
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Definition
| A GENERAL TERM THAT REFER'S TO THE AIR'S WATER VAPOR CONTENT. (SEE RELATIVE HUMIDITY.) |
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Term
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Definition
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Term
| SATURATION VAPOR PRESSURE |
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Definition
| THE MAXIMUM AMOUNT OF WATER VAPOR NECESASRY TO KEEP MOIST AIR IN EQUILIBRIUM WITH A SURFACE OF PURE WATER OR ICE. IT REPRESENTS THE MAXIMUM AMOUNT OF WATER VAPOR THAT THE AIR CAN HOLD AT ANY GIVEN TEMPERATURE AND PRESSURE. (SEE EQUILIBRIUM VAPOR PRESSURE.) |
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Term
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Definition
| THE RATIO OF THE AMOUNT OF WATER VAPOR IN THE AIR COMPARED TO THE AMOUNT REQUIRED FOR SATURATION (AT A PARTICULAR TEMPERATURE AND PRESSURE). THE RATIO OF THE AIR'S ACTUAL VAPOR PRESSURE TO ITS SATURATION VAPOR PRESSURE. |
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Term
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Definition
| A CONDITION WHEREBY THE ATMOSPHERE CONTAINS MORE WATER VAPOR THAN IS NEEDED TO PRODUCE SATURATION WITH RESPECT TO A FLAT SURFACE OF PURE WATER OR ICE, AND THE RELATIVE HUMIDITY IS GREATER THAN 100 PERCENT. |
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Term
| DEW-POINT TEMPERATURE (DEW POINT) |
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Definition
THE TEMPERATURE TO WHICH THE AIR MUST BE COOLED (AT CONSTANT PRESSURE AND CONSTANT WATER VAPOR CONTENT) FOR SATURATION TO OCCUR. |
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Term
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Definition
| THE LOWEST TEMPERAURE THAT CAN BE OBTAINED BY EVAPORATING WATER INTO THE AIR. |
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Term
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Definition
| AN INDEX THAT COMBINES AIR TEMPERATURE AND RELATIVE HUMIDITY TO DETERMINE AN APPARENT TEMPERATURE-HOW HOT IT ACTUALLY FEELS. |
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Term
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Definition
| WHAT THE AIR TEMPERATURE "FEELS LIKE" FOR VARIOUS COMBINATIONS OF AIR TEMPERATURE AND RELATIVE HUMIDITY. |
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Term
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Definition
| AN INSTRUMENT USED TO MEASURE THE WATER VAPOR CONTENT OF THE AIR. IT CONSISTS OF TWO THERMOMETERS (DRY BULB AND WET BULB). AFTER WHIRLING THE INSTRUMENT, THE DEW POINT AND RELATIVE HUMIDITY CAN BE OBTAINED WITH THE AID OF TABLES. |
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Term
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Definition
| AN INSTRUMENT DESIGNED TO MEASURE THE AIR'S WATER VAPOR CONTENT. THE SENSING PART OF THE INSTRUMENT CAN BE HAIR (HAIR HYGROMETER), A PLATE COATED WITH CARBON (ELECTRICAL HYGROMETER), OR AN INFRARED SENSOR (INFRARED HYGROMETER). |
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Term
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Definition
| WATER THAT HAS CONDENSED ONTO OBJECTS NEAR THE GROUND WHEN THEIR TEMPERATURES HAVE FALLEN BELOW THE DEW POINT OF THE SURFACE AIR. |
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Term
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Definition
| (ALSO CALLED HOARFROST) A COVERING OF ICE PRODUCED BY DEPOSITION ON EXPOSED SURFACES WHEN THE AIR TEMPERATURE FALLS BELOW THE FROST POINT. |
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Term
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Definition
| FINE DRY OR WET DUST OR SALT PARTICLES DISPERSED THROUGH A PORTION OF THE ATMOSPHERE. INDIVIDUALLY THESE ARE NOT VISIBLE BUT CUMULATIVELY THEY WILL DIMINISH VISIBILITY. DRY HAZE PARTICLES ARE VERY SMALL, ON THE ORDER OF 0.1 MICROMETERS. WET HAZE PARTICLES ARE LARGER. |
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Term
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Definition
| A CLOUD WITH ITS BASE AT THE EARTH'S SURFACE. |
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Term
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Definition
| FOG PRODUCED OVER LAND WHEN RADIATIONAL COOLING REDUCES THE AIR TEMPERATURE TO OR BELOW ITS DEW POINT. IT IS ALSO KNOWN AS GROUND FOG AND VALLEY FOG. |
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Term
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Definition
| OCCURS WHEN WARM, MOIST AIR MOVES OVER A COLD SURFACE AND THE AIR COOLS TO BELOW ITS DEW POINT. |
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Term
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Definition
| FOG FORMED AS MOIST, STABLE AIR FLOWS UPWARD OVER A TOPOGRAPHIC BARRIER. |
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Term
|
Definition
| FOG PRODUCED WHEN SUFFICIENT WATER VAPOR IS ADDED TO THE AIR BY EVAPORATION, AND THE MOIST AIR MIXES WITH RELATIVELY DRIER AIR. THE TWO COMMON TYPES ARE STEAM FOG, WHICH FORMS WHEN COLD AIR MOVE OVER WARM WATER, AND FRONTAL FOG, WHICH FORMS AS WARM RAINDROPS EVAPORATE IN A COOL AIR MASS. |
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Term
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Definition
| A HIGH CLOUD COMPOSED OF ICE CRYSTALS IN THE FORM OF THIN, WHITE, FEATHERLIKE CLOUDS IN PATCHES, FILAMENTS, OR NARROW BANDS. |
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Term
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Definition
| A HIGH CLOUD THAT APPEARS AS A WHITE PATCH OF CLOUDS WITHOUT SHADOWS. IT CONSISTS OF VERY SMALL ELEMENTS IN THE FORM OF GRAINS OR RIPPLES. |
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Term
|
Definition
| HIGH, THIN, SHEETLIKE CLOUD, COMPOSED OF ICE CRYSTALS. THEY FREQUENTLY COVER THE ENTIRE SKY AND OFTEN PRODUCE A HALO. |
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Term
|
Definition
| A MIDDLE CLOUD, USUALLY WHITE OR GRAY. OFTEN OCCURS IN LAYERS OR PATCHES WITH WAVY, ROUNDED MASSES OR ROLLS. |
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Term
|
Definition
| A MIDDLE CLOUD COMPOSED OF GRAY OR BLUISH SHEETS OR LAYERS OF UNIFORM APPEARANCE. IN THE THINNER REGIONS, THE SUN OR MOON USUALLY APPEARS DIMLY VISIBLE. |
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Term
|
Definition
| A DARK, GRAY CLOUD CHARACTERIZED BY MORE OR LESS CONTINUOUSLY FALLING PRECIPITATION. IT IS RARELY ACCOMPANIED BY LIGHTNING, THUNDER, OR HAIL. |
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Term
|
Definition
| A LOW CLOUD, PREDOMINANTLY STRATIFORM, WITH LOW, LUMPY, ROUNDED MASSES, OFTEN WITH BLUE SKY BETWEEN THEM. |
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Term
|
Definition
| A LOW, GRAY CLOUD LAYER WITH A RATHER UNIFORM BASE WHOSE PRECIPITATION IS MOST COMMONLY DRIZZLE. |
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Term
|
Definition
| A CLOUD IN THE FORM OF INDIVIDUAL, DETACHED DOMES OR TOWERS THAT ARE USUALLY DENSE AND WELL DEFINED. IT HAS A FLAT BASE WITH A BULGING UPPER PART THAT OFTEN RESEMBLES CAULIFLOWER. CUMULUS CLOUDS OF FAIR WEATHER ARE CALLED CUMULUS HUMILIS. THOSE THAT EXHIBIT MUCH VERTICAL GROWTH ARE CALLED CUMULUS CONGESTUS OR TOWERING CUMULUS. |
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Term
|
Definition
| AN EXCEPTIONALLY DENSE AND VERTICALLY DEVELOPED CLOUD, OFTEN WITH A TOP IN THE SHAPE OF AN ANVIL. THE CLOUD IS FREQUENTLY ACCOMPANIED BY HEAVY SHOWERS, LIGHTNING, THUNDER, AND SOMETIMES HAIL. IT IS ALSO KNOWN AS A THUNDERSTORM CLOUD. |
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Term
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Definition
| A CLOUD IN THE SHAPE OF A LENS. |
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Term
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Definition
| A SMOOTH CLOUD IN THE FORM OF A CAP. OCCURS ABOVE, OR IS ATTACHED TO, THE TOP OF A CUMULIFORM CLOUD. ALSO CALLED A CAP CLOUD. |
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Term
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Definition
| CLOUDS THAT LOOK LIKE POUCHES HANGING FROM THE UNDERSIDE OF A CLOUD. |
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Term
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Definition
| (CONDENSATION TRAIL) A CLOUDLIKE STREAMER FREQUENTLY SEEN FORMING BEHIND AIRCRAFT FLYING IN CLEAR, COLD, HUMID AIR. |
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Term
|
Definition
| CLOUDS OF UNKNOWN COMPOSITION THAT HAVE A SOFT, PEARLY LUSTER AND THAT FORM AT ALTITUDES ABOUT 25 TO 30 KM ABOVE THE EARTH'S SURFACE. THEY ARE ALSO CALLED MOTHER-OF-PEARL CLOUDS. |
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Term
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Definition
| WAVY, THIN, BLUISH-WHITE CLOUDS THAT ARE BEST SEEN AT TWILIGHT IN POLAR LATITUDES. THEY FORM AT ALTITUDES ABOUT 80 TO 90 KM ABOVE THE SURFACE. |
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Term
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Definition
| A PROCESS THAT TAKES PLACE WITHOUT A TRANSFER OF HEAT BETWEEN THE SYSTEM (SUCH AS AN AIR PARCEL) AND ITS SURROUNDINGS. IN AN ADIABATIC PROCESS, COMPRESSION ALWAYS RESULTS IN WARMING, AND EXPANSION RESULTS IN COOLING. |
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Term
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Definition
| THE RATE OF CHANGE OF TEMPERATURE IN A RISING OR DESCENDING UNSATURATED AIR PARCEL. THE RATE OF ADIABATIC COOLING OR WARMING IS ABOUT 10 DEGREES C PER 1000 M (5.5 DEGREES F PER 1000 FT). |
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Term
|
Definition
| THE RATE OF CHANGE OF TEMPERATURE IN A RISING OR DESCENDING SATURATED AIR PARCEL. THE RATE OF COOLING OR WARMING VARIES BUT A COMMON VALUE OF 6 DEGREES C PER 1000 M (3.3 DEGREES F PER 1000 FT) IS USED. |
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Term
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Definition
| THE RATE OF DECREASE OF AIR TEMPERATURE WITH ELEVATION. IT IS MOST OFTEN MEASURED WITH A RADIOSONDE. |
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Term
| ABSOLUTELY STABLE ATMOSPHERE |
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Definition
| AN ATMOSPHERIC CONDITION THAT EXISTS WHEN THE ENVIRONMENTAL LAPSE RATE IS LESS THAN THE MOIST ADIABATIC RATE. THIS RESULTS IN A LIFTED PARCEL OF AIR BEING COLDER THAN THE AIR AROUND IT. |
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Term
| ABSOLUTELY UNSTABLE ATMOSPHERE |
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Definition
| AN ATMOSPHERIC CONDITION THAT EXISTS WHEN THE ENVIRONMENTAL LAPSE RATE IS GREATER THAN THE DRY ADIABATIC RATE. THIS RESULTS IN A LIFTED PARCEL OF AIR BEING WARMER THAN THE AIR AROUND IT. |
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Term
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Definition
| THE LEVEL ABOVE THE SURFACE MARKING THE BASE OF A CUMULIFORM CLOUD. |
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Term
| CONDITIONALLY UNSTABLE ATMOSPHERE |
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Definition
| AN ATMOSPHERIC CONDITION THAT EXISTS WHEN THE ENVIRONMENTAL LAPSE RATE IS LESS THAN THE DRY ADIABATIC RATE BUT GREATER THAN THE MOIST ADIABATIC RATE. ALSO CALLED CONDITIONAL INSTABILITY. |
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Term
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Definition
| THE LIFTING OF AIR OVER A TOPOGRAPHIC BARRIER. CLOUDS THAT FORM IN THIS LIFTING PROCESS ARE CALLED OROGRAPHIC CLOUDS. |
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Term
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Definition
| THE REGION ON THE LEESIDE OF A MOUNTAIN WHERE THE PRECIPITATION IS NOTICEABLY LESS THAN ON THE WINDWARD SIDE. |
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Term
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Definition
| ANY FORM OF WATER PARTICLES-LIQUID OR SOLID-THAT FALLS FROM THE ATMOSPHERE AND REACHES THE GROUND. |
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Term
| COLLISION-COALESCENCE PROCESS |
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Definition
| THE PROCESS OF PRODUCING PRECIPITATION BY LIQUID PARTICLES (CLOUD DROPLETS AND RAINDROPS) COLLIDING AND JOINING (COALESCING). |
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Term
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Definition
| THE MERGING OF CLOUD DROPLETS INTO A SINGLE LARGER DROPLET. |
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Term
| ICE-CRYSTAL (BERGERON) PROCESS |
|
Definition
A PROCESS THAT PRODUCES PRECIPITATION. THE PROCESS INVOLVES TINY ICE CRYSTALS IN A SUPERCOOLED CLOUD GROWING LARGER AT THE EXPENSE OF THE SURROUNDING LIQUID DROPLETS. ALSO CALLED THE BERGERON PROCESS. |
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Term
| SUPERCOOLED (WATER DROPLET) |
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Definition
| A CLOUD COMPOSED OF LIQUID DROPLETS AT TEMPERATURES BELOW 0 DEGREES C (32 DEGREES F). WHEN THE CLOUD IS ON THE GROUND IT IS CALLED SUPERCOOLED FOG OR COLD FOG. |
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Term
|
Definition
| PARTICLES THAT ACT AS NUCLEI FOR THE FORMATION OF ICE CRYSTALS IN THE ATMOSPHERE. |
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Term
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Definition
| THE GROWTH OF A PRECIPITATION PARTICLE BY THE COLLISION OF AN ICE CRYSTAL OR SNOWFLAKE WITH A SUPERCOOLED LIQUID DROPLET THAT FREEZES UPON IMPACT. |
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Term
|
Definition
| THE INTRODUCTION OF ARTIFICIAL SUBSTANCES (USUALLY SILVER IODIDE OR DRY ICE) INTO A CLOUD FOR THE PURPOSE OF EITHER MODIFYING ITS DEVELOPMENT OR INCREASING ITS PRECIPITATION. |
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Term
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Definition
| PRECIPITATION IN THE FORM OF LIQUID WATER DROPS THAT HAVE DIAMETERS GREATER THAN THAT OF DRIZZLE. |
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Term
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Definition
| SMALL WATER DROPS BETWEEN 0.2 AND 0.5 MM IN DIAMETER THAT FALL SLOWLY AND REDUCE VISIBILITY MORE THAN LIGHT RAIN. |
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Term
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Definition
| PRECIPITATION THAT FALLS FROM A CLOUD BUT EVAPORATES BEFORE REACHING THE GROUND. (SEE FALLSTREAKS.) |
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Term
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Definition
| INTERMITTENT PRECIPITATION FROM A CUMULIFORM CLOUD, USUALLY OF SHORT DURATION BUT OFTEN HEAVY. |
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Term
|
Definition
| A SOLID FORM OF PRECIPITATION COMPOSED OF ICE CRYSTALS IN COMPLEX HEXAGONAL FORM. |
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Term
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Definition
| FALLING ICE CRYSTALS THAT EVAPORATE BEFORE REACHING THE GROUND. |
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Term
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Definition
| LIGHT SHOWERS OF SNOW THAT FALL INTERMITTENTLY. |
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Term
|
Definition
| (SHOWER) AN INTERMITTENT HEAVY SHOWER OF SNOW THAT GREATLY REDUCES VISIBILITY. |
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Term
|
Definition
| A SEVERE WEATHER CONDITION CHARACTERIZED BY LOW TEMPERATURES AND STRONG WINDS (GREATER THAN 35 MI/HR) BEARING A GREAT AMOUNT OF SNOW EITHER FALLING OR BLOWING. WHEN THESE CONDITIONS CONTINUE AFTER THE FALLING SNOW HAS ENDED, IT IS TERMED A GROUND BLIZZARD. |
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Term
|
Definition
| A TYPE OF PRECIPITATION CONSISTING OF TRANSPARENT PELLETS OF ICE 5 MM OR LESS IN DIAMETER. SAME AS ICE PELLETS. |
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Term
|
Definition
| RAIN OR DRIZZLE THAT FALLS IN LIQUID FORM AND THEN FREEZES UPON STRIKING A COLD OBJECT OR GROUND. BOTH CAN PRODUCE A COATING OF ICE ON OBJECTS WHICH IS CALLED GLAZE. |
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Term
|
Definition
| A WHITE OR MILKY GRANULAR DEPOSIT OF ICE FORMED BY THE RAPID FREEZING OF SUPERCOOLED WATER DROPS AS THEY COME IN CONTACT WITH AN OBJECT IN BELOW-FREEZING AIR. |
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Term
|
Definition
| PRECIPITATION IN THE FORM OF VERY SMALL, OPAQUE GRAINS OF ICE. THE SOLID EQUIVALENT OF DRIZZLE. |
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Term
|
Definition
| WHITE, OPAQUE, APPROXIMATELY ROUND ICE PARTICLES BETWEEN 2 AND 5 MM IN DIAMETER THAT FORM IN A CLOUD EITHER FROM THE STICKING TOGETHER OF ICE CRYSTALS OR FROM THE PROCESS OF ACCRETION. ALSO CALLED GRAUPEL. |
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Term
|
Definition
| TRANSPARENT OR PARTIALLY OPAQUE PARTICLES OF ICE THAT RANGE IN SIZE FROM THAT OF A PEA TO THAT OF GOLF BALLS. |
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Term
|
Definition
| A NONRECORDING RAIN GAUGE WITH AN 8-INCH-DIAMETER COLLECTOR FUNNEL AND A TUBE THAT AMPLIFIES RAINFALL BY TENFOLD. |
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Term
|
Definition
| AN AMOUNT OF PRECIPITATION LESS THAN 0.01 IN. (0.025 CM). |
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Term
|
Definition
| THE DEPTH OF WATER THAT WOULD RESULT FROM THE MELTING OF A SNOW SAMPLE. TYPICALLY, ABOUT 10 INCHES OF SNOW WILL MELT TO 1 INCH OF WATER, PRODUCING A WATER EQUIAVALENT OF 10 TO 1. |
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Term
|
Definition
| AN ELECTRONIC INSTRUMENT USED TO DETECT OBJECTS (SUCH AS FALLING PRECIPITATION) BHY THEIR ABILITY TO REFLECT AND SCATTER MICROWAVES BACK TO A RECEIVER. (SEE ALSO DOPPLER RADAR.) |
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Term
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Definition
| A RADAR THAT DETERMINES THE VELOCITY OF FALLING PRECIPITATION EITHER TOWARD OR AWAY FROM THE RADAR UNIT BY TAKING INTO ACCOUNT THE DOPPLER SHIFT. |
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Term
|
Definition
| (ATMOSPHERIC PRESSURE) THE PRESSURE EXERTED BY THE MASS OF AIR ABOVE A GIVEN POINT, USUALLY EXPRESSED IN MILLIBARS (MB), INCHES OF MERCURY (HG) OR IN HECTOPASCALS (HPA). |
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Term
|
Definition
| A UNIT OF EXPRESSING ATMOSPHERIC PRESSURE. SEA-LEVEL PRESSURE IS NORMALLY CLOSE TO 1013 MB. |
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Term
| STANDARD ATMOSPHERIC PRESSURE |
|
Definition
| A PRESSURE OF 1013.25 MILLIBARS (MB), 29.92 INCHES OF MERCURY (HG), 760 MILLIMETERS (MM) OF MERCURY, 14.7 POUNDS PER SQUARE INCH (LB/IN.2), OR 1013.25 HECTOPASCALS (HPA). |
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Term
|
Definition
| AN INTSRUMENT THAT MEASURES ATMOSPHERIC PRESSURE. THE TWO MOST COMMON BAROMETERS ARE THE MERCURY BAROMETER AND THE ANEROID BAROMETER. |
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Term
|
Definition
| A TYPE OF BAROMETER THAT USES MERCURY TO MEASURE ATMOSPHERIC PRESSURE. THE HEIGHT OF THE MERCURY COLUMN IS A MEASURE OF ATMOSPHERIC PRESSURE. |
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Term
|
Definition
| AN INSTRUMENT DESIGNED TO MEASURE ATMOSPHERIC PRESSURE. IT CONTAINS NO LIQUID. |
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Term
|
Definition
| THE ACTUAL AIR PRESSURE COMPUTED AT THE OBSERVING STATION. |
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Term
|
Definition
| THE ATMOSPHERIC PRESSURE AT MEAN SEA LEVEL. |
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Term
|
Definition
| A LINE CONNECTING POINTS OF EQUAL PRESSURE. |
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|
Term
|
Definition
| A MAP THAT SHOWS THE DISTRIBUTION OF SEA-LEVEL PRESSURE WITH ISOBARS AND WEATHER PHENOMENA. ALSO CALLED A SURFACE CHART. |
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Term
|
Definition
| AN AREA OF HIGH ATMOSPHERIC PRESSURE AROUND WHICH THE WIND BLOWS CLOCKWISE IN THE NORTHERN HEMISPHERE AND COUNTERCLOCKWISE IN THE SOUTHERN HEMISPHERE. ALSO CALLED A HIGH. |
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Term
|
Definition
| SEE EXTRATROPICAL CYCLONE. |
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|
Term
|
Definition
| (CHART) SEE CONSTANT-PRESSURE CHART. |
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|
Term
|
Definition
| A LINE THAT CONNECTS POINTS OF EQUAL ELEVATION ABOVE A REFERENCE LEVEL, MOST OFTEN SEA LEVEL. |
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Term
|
Definition
| AN ELONGATED AREA OF HIGH ATMOSPHERIC PRESSURE. |
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|
Term
|
Definition
| AN ELONGATED AREA OF LOW ATMOSPHERIC PRESSURE. |
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|
Term
|
Definition
| THE RATE OF DECREASE OF PRESSURE PER UNIT OF HORIZONTAL DISTANCE. ON THE SAME CHART, WHEN THE ISOBARS ARE CLOSE TOGETHER, THE PRESSURE GRADIENT IS STEEP. WHEN THE ISOBARS ARE FAR APART, THE PRESSURE GRADIENT IS WEAK. |
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|
Term
|
Definition
| (PGF) THE FORCE DUE TO DIFFERENCES IN PRESSURE WITHIN THE ATMOSPHERE THAT CAUSES AIR TO MOVE AND, HENCE, THE WIND TO BLOW. IT IS DIRECTLY PROPORTIONAL TO THE PRESSURE GRADIENT. |
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Term
|
Definition
| AN APPARENT FORCE OBSERVED ON ANY FREEMOVING OBJECT IN A ROTATING SYSTEM. ON THE EARTH, THIS DEFLECTIVE FORCE RESULTS FROM THE EARTH'S ROTATION AND CAUSES MOVING PARTICLES (INCLUDING THE WIND) TO DEFLECT TO THE RIGHT IN THE NORTHERN HEMISPHERE AND TO THE LEFT IN THE SOUTHERN HEMISPHERE. |
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Term
|
Definition
| A THEORETICAL HORIZONTAL WIND BLOWING IN A STRAIGHT PATH, HORIZONTAL TO THE ISOBARS OR CONTOURS, AT A CONSTANT SPEED. THE GEOSTROPHIC WIND RESULTS WHEN THE CORIOLIS FORCE EXACTLY BALANCES THE HORIZONTAL PRESSURE GRADIENT FORCE. |
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Term
|
Definition
| A THEORETICAL WIND THAT BLOWS PARALLEL TO CURVED ISOBARS OR CONTOURS. |
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Term
|
Definition
| THE RADIAL FORCE REQUIRED TO KEEP AN OBJECT MOVING IN A CIRCULAR PATH. IT IS DIRECTED TOWARD THE CENTER OF THAT CURVED PATH. |
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Term
|
Definition
| A TYPE OF ATMOSPHERIC CIRCULATION PATTERN IN WHICH THE NORTH-SOUTH COMPONENT OF THE WIND IS PRONOUNCED. |
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Term
|
Definition
| A WIND THAT HAS A PREDOMINANT WEST-TO-EAST COMPONENT. |
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|
Term
|
Definition
| THE ATMOSPHERIC LAYER NEAR THE SURFACE USUALLY EXTENDING UP TO ABOUT 1 KM (3300 FT) WHERE THE WIND IS INFLUENCED BY FRICTION OF THE EARTH'S SURFACE AND OBJECTS ON IT. ALSO CALLED THE ATMOSPHERIC BOUNDARY LAYER AND PLANETARY BOUNDARY LAYER. |
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Term
|
Definition
| THE STATE OF THE ATMOSPHERE WHEN THERE IS A BALANCE BETWEEN THE VERTICAL PRESSURE GRADIENT FORCE AND THE DOWNWARD PULL OF GRAVITY. |
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Term
|
Definition
| A BREEZE THAT BLOWS FROM THE WATER ONTO THE LAND. OPPOSITE OF AN OFFSHORE WIND. |
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Term
|
Definition
| A BREEZE THAT BLOWS FROM THE LAND OUT OVER THE WATER. OPPOSITE OF AN ONSHORE WIND. |
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Term
|
Definition
| THE WIND DIRECTION MOST FREQUENTLY OBSERVED DURING A GIVEN PERIOD. |
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Term
|
Definition
| A DIAGRAM THAT SHOWS THE PERCENT OF TIME THAT THE WIND BLOWS FROM DIFFERENT DIRECTIONS AT A GIVEN LOCATION OVER A GIVEN TIME. |
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Term
|
Definition
| AN INSTRUMENT USED TO INDICATE WIND DIRECTION. |
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Term
|
Definition
| AN INSTRUMENT DESIGNED TO MEASURE WIND SPEED. |
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Term
|
Definition
| A WIND INSTRUMENT THAT INDICATES OR RECORDS BOTH WIND SPEED AND WIND DIRECTION. ALSO CALLED A SKYVANE. |
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|
Term
|
Definition
| A DOPPLER RADAR CAPABLE OF MEASURING THE TURBULENT EDDIES THAT MOVE WITH THE WIND. BECAUSE OF THIS, IT IS ABLE TO PROVIDE A VERTICAL PICTURE OF WIND SPEED AND WIND DIRECTION. |
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Term
|
Definition
| THE HIERARCHY OF ATMOSPHERIC CIRCULATIONS FROM TINY GUSTS TO GIANT STORMS. |
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Term
|
Definition
| THE SMALLEST SCALE OF ATMOSPHERIC MOTIONS. |
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|
Term
|
Definition
| THE SCALE OF METEORLOGICAL PHENOMENA THAT RANGE IN SIZE FROM A FEW KM TO ABOUT 100 KM. IT INCLUDES LOCAL WINDS, THUNDERSTORMS, AND TORNADOES. |
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Term
|
Definition
| THE TYPICAL WEATHER MAP SCALE THAT SHOWS FEATURES SUCH AS HIGH- AND LOW-PRESSURE AREAS AND FRONTS OVER A DISTANCE SPANNING A CONTINENT. ALSO CALLED THE CYCLONIC SCALE. |
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Term
|
Definition
| THE LARGEST SCALE OF ATMOSPHERIC MOTION. SOMETIMES CALLED THE GLOBAL SCALE. |
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Term
|
Definition
| TURBULENT EDDIES THAT FORM DOWNWIND OF A MOUNTAIN CHAIN, CREATING HAZARDOUS FLYING CONDITIONS. |
|
|
Term
|
Definition
| THE RATE OF CHANGE OF WIND SPEED OR WIND DIRECTION OVER A GIVEN DISTANCE. |
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|
Term
| CLEAR AIR TURBULENCE (CAT) |
|
Definition
| TURBULENCE ENCOUNTERED BY AIRCRAFT FLYING THROUGH CLOUDLESS SKIES. THERMALS, WIND SHEAR, AND JET STREAMS CAN EACH BE A FACTOR IN PRODUCING CAT. |
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Term
|
Definition
| AIR FLOW RESULTING PRIMARILY FROM THE HEATING AND COOLING OF AIR. |
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|
Term
|
Definition
| A COASTAL LOCAL WIND THAT BLOWS FROM THE OCEAN ONTO THE LAND. THE LEADING EDGE OF THE BREEZE IS TERMED A SEA BREEZE FRONT. |
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|
Term
|
Definition
| A COASTAL BREEZE THAT BLOWS FROM LAND TO SEA, USUALLY AT NIGHT. |
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Term
|
Definition
| A WIND SYSTEM THAT REVERSES DIRECTION BETWEEN WINTER AND SUMMER. USUALLY THE WIND BLOWS FROM LAND TO SEA IN WINTER AND FROM SEA TO LAND IN SUMMER. |
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Term
|
Definition
|
|
Term
|
Definition
| A LOCAL WIND SYSTEM OF A MOUNTAIN VALLEY THAT BLOWS DOWNHILL (MOUNTAIN BREEZE) AT NIGHT AND UPHILL (VALLEY BREEZE) DURING THE DAY. |
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Term
|
Definition
ANY WIND BLOWING DOWNSLOPE. IT IS USUALLY COLD. |
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|
Term
|
Definition
| A WARM, DRY WIND ON THE EASTERN SIDE OF THE ROCKY MOUNTAINS. IN THE ALPS, THE WIND IS CALLED A FOEHN. |
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Term
|
Definition
| A WARM, DRY WIND THAT BLOWS INTO SOUTHERN CALIFORNIA FROM THE EAST OFF THE ELEVATED DESERT PLATEAU. ITS WARMTH IS DERIVED FROM COMPRESSIONAL HEATING. |
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Term
|
Definition
| A DUST OR SANDSTORM THAT FORMS AS COLD DOWNDRAFTS FROM A THUNDERSTORM TURBULENTLY LIFT DUST AND SAND INTO THE AIR. |
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Term
|
Definition
A SMALL BUT RAPIDLY ROTATING WIND MADE VISIBLE BY THE DUST, SAND, AND DEBRIS IT PICKS UP FROM THE SURFACE. IT DEVELOPS BEST ON CLEAR, DRY, HOT AFTERNOONS. |
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Term
| GENERAL CIRCULATION OF THE ATMOSPHERE |
|
Definition
| LARGE-SCALE ATMOSPHERIC MOTIONS OVER THE ENTIRE EARTH. |
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Term
|
Definition
| A THERMAL CIRCULATION PROPOSED BY GEORGE HADLEY TO EXPLAIN THE MOVEMENT OF THE TRADE WINDS. IT CONSISTS OF RISING AIR NEAR THE EQUATOR AND SINKING AIR NEAR 30 DEGREES LATITUDE. |
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|
Term
|
Definition
THE REGION NEAR THE EQUATOR THAT IS CHARACTERIZED BY LOW PRESSURE AND LIGHT, SHIFTING WINDS. |
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|
Term
|
Definition
A SEMIPERMANENT HIGH IN THE SUBTROPICAL HIGH-PRESSURE BELT CENTERED NEAR 30 DEGREES LATITUDE. THE BERMUDA HIGH IS LOCATED OVER THE ATLANTIC OCEAN OFF THE EAST COAST OF NORTH AMERICA. THE PACIFIC HIGH IS LOCATED OFF THE WEST COAST OF NORTH AMERICA. |
|
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Term
|
Definition
| THE WINDS THAT OCCUPY MOST OF THE TROPICS AND BLOW FROM THE SUBTROPICAL HIGHS TO THE EQUATORIAL LOW. |
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|
Term
| INTERTROPICAL CONVERGENCE ZONE (ITCZ) |
|
Definition
| THE BOUNDARY ZONE SEPARATING THE NORTHEAST TRADE WINDS OF THE NORTHERN HEMISPHERE FROM SOUTHEAST TRADE WINDS OF THE SOUTHERN HEMISPHERE. |
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Term
|
Definition
| THE DOMINANT WESTERLY WINDS THAT BLOW IN THE MIDDLE LATITUDES ON THE POLEWARD SIDE OF THE SUBTROPICAL HIGH-PRESSURE AREAS. |
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|
Term
|
Definition
| A SEMIPERMANENT, SEMICONTINUOUS FRONT THAT SEPARATES TROPICAL AIR MASSES FROM POLAR AIR MASSES. |
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|
Term
|
Definition
| A BELT OF LOW PRESSURE LOCATED BETWEEN 50 DEGREES AND 70 DEGREES LATITUDE. IN THE NORTHERN HEMISPHERE, THIS "BELT" CONSISTS OF THE ALEUTIAN LOW IN THE NORTH PACIFIC AND THE ICELANDIC LOW IN THE NORH ATLANTIC. IN THE SOUTHERN HEMISPHERE, IT EXISTS AROUND THE PERIPHERY OF THE ANTARCTIC CONTINENT. |
|
|
Term
|
Definition
| A SHALLOW BODY OF EASTERLY WINDS LOCATED AT HIGH LATITUDES POLEWARD OF THE SUBPOLAR LOW. |
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|
Term
|
Definition
|
|
Term
|
Definition
|
|
Term
|
Definition
| THE SUBPOLAR LOW-PRESSURE AREA THAT IS CENTERED NEAR ICELAND ON CHARTS THAT SHOW MEAN SEA-LEVEL PRESSURE. |
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|
Term
|
Definition
THE SUBPOLAR LOW-PRESSURE AREA THAT IS CENTERED NEAR THE ALEUTIAN ISLANDS ON CHARTS THAT SHOW MEAN SEA-LEVEL PRESSURE. |
|
|
Term
|
Definition
| A STRONG, SHALLOW AREA OF HIGH PRESSURE THAT FORMS OVER SIBERIA IN WINTER. |
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|
Term
|
Definition
| RELATIVELY STRONG WINDS CONCENTRATED WITHIN A NARROW BAND IN THE ATMOSPHERE. |
|
|
Term
|
Definition
| THE JET STREAM TYPICALLY FOUND BETWEEN 20 DEGREES AND 30 DEGREES LATITUDE AT ALTITUDES BETWEEN 12 AND 14 KM. |
|
|
Term
|
Definition
| (POLAR JET) THE JET STREAM THAT IS ASSOICATED WITH THE POLAR FRONT IN MIDDLE AND HIGH LATITUDES. IT IS USUALLY LOCATED AT ALTITUDES BETWEEN 9 AND 12 KM. |
|
|
Term
|
Definition
| THE RISING OF WATER (USUALLY COLD) TOWARD THE SURFACE FROM THE DEEPER REGIONS OF A BODY OF WATER. |
|
|
Term
|
Definition
AN EXTENSIVE OCEAN WARMING THAT BEGINS ALONG THE COAST OF PERU AND ECUADOR AND EXTENDS WESTWARD OVER THE TROPICAL PACIFIC. MAJOR EL NINO EVENTS, OR STRONG EL NINOS, OCCUR ONCE EVERY 2 TO 7 YEARS AS A CURRENT OF NUTRIENT-POOR TROPICAL WATER MOVES SOUTHWARD ALONG THE WEST COAST OF SOUTH AMERICA. |
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Term
|
Definition
| THE REVERSAL OF SURFACE AIR PRESSURE AT OPPOSITE ENDS OF THE TROPICAL PACIFIC OCEAN THAT OCCURS DURING MAJOR EL NINO EVENTS. |
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|
Term
|
Definition
| (EL NINO/SOUTHERN OSCIALLATION) A CONDITION IN THE TROPICAL PACIFIC WHEREBY THE REVERSAL OF SURFACE AIR PRESSURE AT OPPOSITE ENDS OF THE PACIFIC OCEAN INDUCES WESTERLY WINDS, A STRENGTHENING OF THE EQUATORIAL COUNTERCURRENT, AND EXTENSIVE OCEAN WARMING. |
|
|
Term
|
Definition
| A CONDITION WHERE THE CENTRAL AND EASTERN TROPICAL PACIFIC OCEAN TURNS COOLER THAN NORMAL. |
|
|
Term
|
Definition
| A LINKAGE BETWEEN WEATHER CHANGES OCCURING IN WIDELY SEPARATED REGIONS OF THE WORLD. |
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|
Term
| NORTH ATLANTIC OSCILLATION (NAO) |
|
Definition
| A REVERSAL OF ATMOSPHERIC PRESSURE OVER THE ATLANTIC OCEAN THAT INFLUENCES THE WEATHER OVER EUROPE AND OVER EASTERN NORTH AMERICA. |
|
|
Term
|
Definition
| A REVERSAL OF ATMOSPHERIC PRESSURE OVER THE ARCTIC THAT PRODUCES CHANGES IN THE UPPER-LEVEL WESTERLY WINDS OVER NORTHERN LATITUDES. THESE CHANGES IN UPPER-LEVEL WINDS INFLUENCE WINTER WEATHER PATTERNS OVER NORTH AMERICA, GREENLAND, AND EUROPE. |
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|
Term
| PACIFIC DECADAL OSCIALLTION (PDO) |
|
Definition
| A REVERSAL IN OCEAN SURFACE TEMPERATURES THAT OCCURS EVERY 20 TO 30 YEARS OVER THE NORTHERN PACIFIC OCEAN. |
|
|
Term
|
Definition
| A LARGE BODY OF AIR THAT HAS SIMILAR HORIZONTAL TEMPERATURE AND MOISTURE CHARACTERISTICS. |
|
|
Term
SOURCE REGION (FOR AIR MASSES) |
|
Definition
| REGIONS WHERE AIR MASSES ORIGINATE AND ACQUIRE THEIR PROPERTIES OF TEMPERATURE AND MOISTURE. |
|
|
Term
| CONTINENTAL POLAR (AIR MASS) |
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Definition
| AN AIR MASS CHARACTERIZED BY LOW TEMPERATURES AND DRY AIR. NOT AS COLD AS ARCTIC AIR MASSES. |
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Term
| CONTINENTAL ARCTIC (AIR MASS) |
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Definition
| AN AIR MASS CHARACTERIZED BY EXTREMELY LOW TEMPERATURES AND VERY DRY AIR. |
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Term
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Definition
| LOCALIZED SNOWSTORMS THAT FORM ON THE DOWNWIND SIDE OF A LAKE. SUCH STORMS ARE COMMON IN LATE FALL AND EARLY WINTER NEAR THE GREAT LAKES AS COLD, DRY AIR PICKS UP MOISTURE AND WARMTH FROM THE UNFROZEN BODIES OF WATER. |
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Term
| MARITIME POLAR (AIR MASS) |
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Definition
| AN AIR MASS CHARACTERIZED BY LOW TEMPERATURES AND HIGH HUMIDITY. |
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Term
| MARITIME TROPICAL (AIR MASS) |
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Definition
| AN AIR MASS CHARACTERIZED BY HIGH TEMPERATURES AND HIGH HUMIDITY. |
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Term
| CONTINENTAL TROPICAL (AIR MASS) |
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Definition
| AN AIR MASS CHARACTERIZED BY HIGH TEMPERATURES AND LOW HUMIDITY. |
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Term
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Definition
| THE TRANSITION ZONE BETWEEN TWO DISTINCT AIR MASSES. |
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Term
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Definition
| A FRONT THAT IS NEARLY STATIONARY WITH WINDS BLOWING ALMOST PARALLEL AND FROM OPPOSITE DIRECTIONS ON EACH SIDE OF THE FRONT. |
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Term
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Definition
| A TRANSITION ZONE WHERE A COLD AIR MASS ADVANCES AND REPLACES A WARM AIR MASS. |
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Term
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Definition
| A COLD FRONT MOVING SOUTH OR SOUTHWEST ALONG THE ATLANTIC SEABOARD OF THE UNITED STATES. |
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Term
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Definition
| A FRONT THAT MOVES IN SUCH A WAY THAT WARM AIR REPLACES COLD AIR. |
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Term
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Definition
| A CONDITION THAT OCCURS WHEN AIR MOVES UP AND OVER ANOTHER LAYER OF AIR. |
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Term
| OCCLUDED FRONT (OCCLUSION) |
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Definition
A COMPLEX FRONTAL SYSTEM THAT IDEALLY FORMS WHEN A COLD FRONT OVERTAKES A WARM FRONT. WHEN THE AIR BEHIND THE FRONT IS COLDER THAN THE AIR AHEAD OF IT, THE FRONT IS CALLED A COLD OCCLUSION. WHEN THE AIR BEHIND THE FRONT IS MILDER THAN THE AIR AHEAD OF IT, IT IS CALLED A WARM OCCLUSION. |
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Term
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Definition
| A THEORY DEVELOPED BY A GROUP OF SCANDANAVIAN METEOROLOGISTS THAT EXPLAINS THE FORMATION, DEVELOPMENT, AND OVERALL LIFE HISTORY OF CYCLONIC STORMS THAT FORM ALONG THE POLAR FRONT. |
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Term
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Definition
| AN EXTRATROPICAL CYCLONE THAT FORMS AND MOVES ALONG A FRONT. THE CIRCULATION OF WINDS ABOUT THE CYCLONE TENDS TO PRODUCE A WAVELIKE DEFORMATION ON THE FRONT. |
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Term
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Definition
| A WAVELIKE DEFORMATION ALONG A FRONT IN THE LOWER LEVELS OF THE ATMOSPHERE. THOSE THAT DEVELOP INTO STORMS ARE TERMED UNSTABLE WAVES, WHILE THOSE THAT DO NOT ARE CALLED STABLE WAVES. |
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Term
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Definition
| THE STAGE OF DEVELOPMENT OF A WAVE CYCLONE (MID-LATITUDE CYCLONIC STORM) WHERE A COLD FRONT AND A WARM FRONT EXIST, BUT NO OCCLUDED FRONT. THE CENTER OF LOWEST PRESSURE IN THE WAVE IS LOCATED AT THE JUNCTION OF THE TWO FRONTS. |
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Term
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Definition
| THE DEVELOPMENT OR STRENGTHENING OF MIDDLE-LATITUDE (EXTRATROPICAL) CYCLONES. |
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Term
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Definition
| STORM SYSTEMS (EXTRATROPICAL CYCLONES) THAT FORM ON THE DOWNWIND (LEE) SIDE OF A MOUNTAIN CHAIN. IN THE UNITED STATES LEE-SIDE LOWS FREQUENTLY FORM ON THE EASTERN SIDE OF THE ROCKIES AND SIERRA NEVADA MOUNTAINS. |
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Term
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Definition
| A NAME GIVEN TO A STRONG, STEADY WIND FROM THE NORTHEAST THAT IS ACCOMPANIED BY RAIN AND INCLEMENT WEATHER. IT OFTEN DEVELOPS WHEN A STORM SYSTEM MOVES NORTHEASTWARD ALONG THE COAST OF NORTH AMERICA. ALSO CALLED NOR'EASTER. |
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Term
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Definition
| AN ATMOSPHERIC CONDITION THAT EXISTS WHEN THE WINDS CAUSE A HORIZONTAL NET INFLOW OF AIR INTO A SPECIFIED REGION. |
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Term
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Definition
| AN ATMOSPHERIC CONDITION THAT EXISTS WHEN THE WINDS CAUSE A HORIZONTAL NET OUTFLOW OF AIR FROM A SPECIFIC REGION. |
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Term
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Definition
| A REGION OF HIGH WIND SPEED THAT MOVES THROUGH THE AXIS OF A JET STREAM. ALSO CALLED JET MAXIMUM. |
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Term
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Definition
| THE TRANSFER OF HEAT BY MOLECULAR ACITIVITY FROM ONE SUBSTANCE TO ANOTHER, OR THROUGH A SUBSTANCE. TRANSFER IS ALWAYS FROM WARMER TO COLDER REGIONS. |
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Term
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Definition
| MOTIONS IN A FLUID THAT RESULT IN THE TRANSPORT AND MIXING OF THE FLUID'S PROPERTIES. IN METEOROLOGY, CONVECTION USUALLY REFERES TO ATMOSPHERIC MOTIONS THAT ARE PREDOMINANTLY VERTICAL, SUCH AS RISING AIR CURRENTS DUE TO SURFACE HEATING. THE RISING OF HEATED SURFACE AIR AND THE SINKING OF COOLER AIR ALOFT IS OFTEN CALLED FREE CONVECTION. (COMPARED WITH FORCED CONVECTION.) |
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Term
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Definition
| INTENSE THUNDERSTORMS CAPABLE OF PRODUCING HEAVY SHOWERS, FLASH FLOODS, HAIL, STRONG AND GUSTY SURFACE WINDS, AND TORNADOES. |
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Term
| ORDINARY CELL THUNDERSTORMS |
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Definition
| (FORMERLY CALLED AIR-MASS THUNDERSTORM) A THUNDERSTORM PRODUCED BY LOCAL CONVECTION WITHIN A CONDITIONALLY UNSTABLE AIR MASS. IT OFTEN FORMS IN THE AFTERNOON AND DOES NOT REACH THE INTENSITY OF A SEVERE THUNDERSTORM. |
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Term
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Definition
| THE INITIAL STAGE IN THE DEVELOPMENT OF AN ORDINARY CELL THUNDERSTORM IN WHICH RISING, WARM, HUMID AIR DEVELOPS INTO A CUMULUS CLOUD. |
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Term
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Definition
| THE SECOND STAGE IN THE THREE-STAGE CYCLE OF AN ORDINARY THUNDERSTORM. THIS MATURE STAGE IS CHARACTERIZED BY HEAVY SHOWERS, LIGHTNING, THUNDER, AND VIOLENT VERTICAL MOTIONS INSIDE CUMULONIMBUS CLOUDS. |
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Term
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Definition
| THE FINAL STAGE OF THE DEVELOPMENT OF AN ORDINARY CELL THUNDERSTORM WHEN DOWNDRAFTS EXIST THROUGHOUT THE CUMULONIMBUS CLOUD. |
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Term
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Definition
| THUNDERSTORMS OFTEN IN A LINE, EACH OF WHICH MAY BE IN A DIFFERENT STAGE OF ITS LIFE CYCLE. |
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Term
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Definition
| AN ENORMOUS SEVERE THUNDERSTORM THAT CONSISTS PRIMARILY OF A SINGLE ROTATING UPDRAFT. ITS ORGANIZED INTERNAL STRUCTURE ALLOWS THAT STORM TO MAINTAIN ITSELF FOR SEVERAL HOURS. THE STORM CAN PRODUCE LARGE HAIL AND DANGEROUS TORNADOES. |
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Term
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Definition
| A LINE OF THUNDERSTORMS THAT FORM ALONG A COLD FRONT OR OUT AHEAD OF IT. |
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Term
| MESOSCALE CONVECTIVE COMPLEXES (MCCS) |
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Definition
| A LARGE ORGANIZED CONVECTIVE WEATHER SYSTEM COMPRISED OF A NUMBER OF INDIVIDUAL THUNDERSTORMS. THE SIZE OF AN MCC CAN BE 1000 TIMES LARGER THAN AN INDIVIDUAL ORDINARY THUNDERSTORM. |
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Term
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Definition
| A BOUNDARY THAT SEPARATES WARM, DRY AIR FROM WARM, MOIST AIR. IT USUALLY REPRESENTS A ZONE OF INSTABILITY ALONG WHICH THUNDERSTORMS FORM. |
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Term
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Definition
| A BOUNDARY THAT SEPARATES A COLD DOWNDRAFT OF A THUNDERSTORM FROM WARM, HUMID SURFACE AIR. ON THE SURFACE ITS PASSAGE RESEMBLES THAT OF A COLD FRONT. |
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Term
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Definition
| A DENSE, ARCH-SHAPED, OMINOUS-LOOKING CLOUD THAT OFTEN FORMS ALONG THE LEADING EDGE OF A THUNDERSTORM'S GUST FRONT, ESPECIALLY WHEN STABLE AIR RISES UP AND OVER COOLER AIR AT THE SURFACE. ALSO CALLED AN ARCUS CLOUD. |
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Term
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Definition
| A DENSE, CYLINDRICAL, ELONGATED CLOUD THAT APPEARS TO SLOWLY SPIN ABOUT A HORIZONTAL AXIS BEHIND THE LEADING EDGE OF A THUNDERSTORM'S GUST FRONT. |
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Term
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Definition
A SURFACE BOUNDARY SEPARATING COOLER MORE-DENSE AIR FROM WARMER LESS-DENSE AIR. OUTFLOW BOUNDARIES FORM BY THE HORIZONTAL SPREADING OF COOL AIR THAT ORIGINATED INSIDE A THUNDERSTORM. |
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Term
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Definition
| A SEVERE LOCALIZED DOWNDRAFT THAT CAN BE EXPERIENCED BENEATH A SEVERE THUNDERSTORM. (COMPARE MICROBURST AND MACROBURST.) |
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Term
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Definition
| A STRONG LOCALIZED DOWNDRAFT (DOWNBURST) LESS THAN 4 KM WIDE THAT OCCURS BENEATH THUNDERSTORMS. A STRONG DOWNBURST GREATER THAN 4 KM ACROSS IS CALLED A MACROBURST. |
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Term
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Definition
| STRONG, DAMAGING STRAIGHT-LINE WINDS ASSOCIATED WITH A CLUSTER OF SEVERE THUNDERSTORMS THAT MOST OFTEN FORM IN THE EVENING OR AT NIGHT. |
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Term
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Definition
| A LINE OF THUNDERSTORMS ON A RADAR SCREEN THAT APPEARS IN THE SHAPE OF A BOW. BOW ECHOES ARE OFTEN ASSOCIATED WITH DAMAGING STRAIGHT-LINE WINDS AND SMALL TORNADOES. |
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Term
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Definition
| A SUDDEN INCREASE IN SURFACE AIR TEMPERATURE OFTEN ACCOMPANIED BY EXTREME DRYING. A HEAT BURST IS ASSOICATED WITH THE DOWNDRAFT OF A THUNDERSTORM, OR A CLUSTER OF THUNDERSTORMS. |
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Term
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Definition
| A FLOOD THAT RISES AND FALLS QUITE RAPIDLY WITH LITTLE OR NO ADVANCE WARNING, USUALLY AS THE RESULT OF INTENSE RAINFALL OVER A RELATIVELY SMALL AREA. |
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Term
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Definition
| A VISIBLE ELECTRICAL DISCHARGE PRODUCED BY THUNDERSTORMS. |
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Term
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Definition
| THE SOUND DUE TO RAPIDLY EXPANDING GASES ALONG THE CHANNEL OF A LIGHTNING DISCHARGE. |
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Term
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Definition
| A LOUD EXPLOSIVE-LIKE SOUND CAUSED BY A SHOCK WAVE EMANATING FROM AN AIRCRAFT (OR ANY OBJECT) TRAVELING AT OR ABOVE THE SPEED OF SOUND. |
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Term
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Definition
| AN INITIAL DISCHARGE OF ELECTRONS THAT PROCEEDS INTERMITTENTLY TOWARDS THE GROUND IN A SERIES OF STEPS IN A CLOUD-TO-GROUND LIGHTNING STROKE. |
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Term
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Definition
| THE LUMINOUSE LIGHTNING STROKE THAT PROPOGATES UPWARD FROM THE EARTH TO THE BASE OF A CLOUD. |
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Term
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Definition
| THE DISCHARGE OF ELECTRONS THAT PROCEEDS INTERMITTENTLY TOWARD THE GROUND ALONG THE SAME IONIZED CHANNEL TAKEN BY THE INITIAL LIGHTNING STROKE. |
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Term
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Definition
| LIGHTNING THAT OCCURS WITH THUNDERSTORMS THAT PRODUCE LITTLE, IF ANY, APPRECIABLE PRECIPITATION THAT REACHES THE SURFACE. |
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Term
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Definition
| DISTANT LIGHTNING THAT ILLUMINATES THE SKY BUT IS TOO FAR AWAY FOR ITS THUNDER TO BE HEARD. |
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Term
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Definition
| A BRIGHT ELECTRIC DISCHARGE THAT IS PROJECTED FROM OBJECTS (USUALLY POINTED) WHEN THEY ARE IN A STRONG ELECTRIC FIELD, SUCH AS DURING A THUNDERSTORM. |
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Term
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Definition
AN INTENSE, ROTATING COLUMN OF AIR THAT OFTEN PROTRUDES FROM A CUMULONIMBUS CLOUD IN THE SHAPE OF A FUNNEL OR A ROPE WHOSE CIRCULATION IS PRESENT ON THE GROUND. (SEE FUNNEL CLOUD.) |
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Term
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Definition
| A TORNADO WHOSE CIRCULATION HAS NOT REACHED THE GROUND. OFTEN APPEARS AS A ROTATING CONELIKE CLOUD THAT EXTENDS DOWNWARD FROM THE BASE OF A THUNDERSTORM. |
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Term
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Definition
| A SERIES OF TORNADOES THAT FORMS WITHIN A PARTICULAR REGION-A REGION THAT MAY INCLUDE SEVERAL STATES. OFTEN ASSOCIATED WITH WIDESPREAD DAMAGE AND DESTRUCTION. |
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Term
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Definition
| SMALL, RAPIDLYD ROTATING WHIRLS PERHAPS 10 M IN DIAMETER THAT ARE FOUND WITHIN LARGE TORNADOES. |
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Term
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Definition
| A FORECAST ISSUED TO ALERT THE PUBLIC THAT TORNADOES MAY DEVELOP WITHIN A SPECIFIED AREA. |
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Term
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Definition
| A WARNING ISSUED WHEN A TORNADO HAS ACTUALLY BEEN OBSERVED EITHER VIRTUALLY OR ON A RADAR SCREEN. IT IS ALSO ISSUED WHEN THE FORMATION OF TORNADOES IS IMMINENT. |
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Term
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Definition
| A SCALE DEVELOPED BY T. THEODORE FUJITA FOR CLASSIFYING TORNADOES ACCORDING TO THE DAMAGE THEY CAUSE AND THEIR ROTATIONAL WIND SPEED. |
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Term
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Definition
| TORNADOES THAT OCCUR WITHIN SUPERCELL THUNDERSTORMS THAT CONTAIN WELL-DEVELOPED MID-LEVEL MESOCYCLONES. |
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Term
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Definition
| A VERTICAL COLUMN OF CYCLONICALLY ROTATING AIR WITHIN A SUPERCELL THUNDERSTORM. |
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Term
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Definition
| THE SHAPE OF AN ECHO ON A DOPPLER RADAR SCREEN THAT INDICATES THE POSSIBLE PRESENCE OF A TORNADO. |
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Term
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Definition
| AN AREA OF ROTATING CLOUDS THAT EXTENDS BENEATH A SUPERCELL THUNDERSTORM AND FROM WHICH A FUNNEL CLOUD MAY APPEAR. ALSO CALLED A COLLAR CLOUD AND PEDESTAL CLOUD. |
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Term
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Definition
| A TORNADO THAT OCCURS WITH A CLOUD THAT IS OFTEN IN ITS GROWING STAGE AND ONE THAT DOES NOT CONTAIN A MID-LEVEL MESOCYCLONE OR WALL CLOUD. LANDSPOUTS AND GUSTANADOES ARE EXAMPLES OF NONSUPERCELL TORNADOES. |
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Term
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Definition
| A RELATIVELY WEAK TORNADO ASSOCIATED WITH A THUNDERSTORM'S OUTFLOW. IT MOST OFTEN FORMS ALONG THE GUST FRONT. |
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Term
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Definition
| RELATIVELY WEAK NONSUPERCELL TORNADO THAT ORIGINATES WITH A CUMULIFORM CLOUD IN ITS GROWTH STAGE AND WITH A CLOUD THAT DOES NOT CONTAIN A MID-LEVEL MESOCYCLONE. ITS SPIN ORIGINATES NEAR THE SURFACE. LANDSPOUTS OFTEN LOOK LIKE WATERSPOUTS OVER LAND. |
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Term
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Definition
| AN ACRONYM FOR NEXT GENERATION WEATHER RADAR. THE MAIN COMPONENT OF NEXRAD IS THE WSR 88-D, DOPPLER RADAR. |
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Term
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Definition
| A COLUMN OF ROTATING WIND OVER WATER THAT HAS CHARACTERISTICS OF A DUST DEVIL AND TORNADO. |
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Term
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Definition
| A LINE THAT SHOWS THE WIND FLOW PATTERN. |
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Term
| TROPICAL WAVE (EASTERLY WAVE) |
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Definition
| A MIGRATORY WAVELIKE DISTURBANCE IN THE TROPICAL EASTERLIES. TROPICAL WAVES OCCASIONALLY INTENSIFY INTO TROPICAL CYCLONES. THEY ARE ALSO CALLED EASTERLY WAVES. |
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Term
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Definition
| A TROPICAL CYCLONE HAVING WINDS IN EXCESS OF 64 KNOTS (74 MI/HR). |
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Term
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Definition
| A HURRICAN THAT FORMS IN THE WESTERN PACIFIC OCEAN. |
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Term
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Definition
| THE GENERAL TERM FOR STORMS (CYCLONES) THAT FORM OVER WARM TROPICAL OCEANS. |
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Term
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Definition
| A REGION IN THE CENTER OF A HURRICANE (TROPICAL STORM) WHERE THE WINDS ARE LIGHT AND SKIES ARE CLEAR TO PARTLY CLOUDY. |
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Term
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Definition
| A WALL OF DENSE THUNDERSTORMS THAT SURROUNDS THE EYE OF A HURRICANE. |
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Term
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Definition
| A TEMPERATURE INVERSION FREQUENTLY FOUND IN THE SUBTROPICS OVER THE EASTERN PORTIONS OF THE TROPICAL OCEANS. |
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Term
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Definition
| A MASS OF THUNDERSTORMS AND CLOUDS GENERALLY WITH A CYCLONIC WIND CIRCULATION OF BETWEEN 20 AND 34 KNOTS. |
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Term
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Definition
| ORGANIZED THUNDERSTORMS WITH A CYCLONIC WIND CIRCULATION BETWEEN 35 AND 64 KNOTS. |
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Term
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Definition
| NET SURFACE WATER TRANSPORT DUE TO THE EKMAN SPIRAL. IN THE NORTHERN HEMISPHERE THE TRANSPORT IS 90 DEGREES TO THE RIGHT OF THE SURFACE WIND DIRECTION. |
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Term
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Definition
| AN ABNORMAL RISE OF THE SEA ALONG A SHORE; PRIMARILY DUE TO THE WINDS OF A STORM, ESPECIALLY A HURRICANE. |
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Term
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Definition
| A SCALE RELATING TO A HURRICANE'S CENTRAL PRESSURE AND WINDS TO THE POSSIBLE DAMAGE IT IS CAPABLE OF INFLICTING. |
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Term
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Definition
| A TROPICAL CYCLONE (TYPHOON) IN THE WESTERN PACIFIC THAT HAS SUSTAINED WINDS OF 130 KNOTS OR GREATER. |
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Term
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Definition
| A HURRICANE WATCH INDICATES THAT A HURRICANE POSES A THREAT TO AN AREA (OFTEN WITHIN SEVERAL DAYS) AND RESIDENTS OF THE WATCH AREA SHOULD BE PREPARED. |
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Term
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Definition
| A WARNING GIVEN WHEN IT IS LIKELY THAT A HURRICAN WILL STRIKE AN AREA WITHIN 24 HOURS. |
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Term
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Definition
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Term
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Definition
| THE PROCESS BY WHICH SMALL PARTICLES IN THE ATMOSPHERE DEFLECT RADIATION FROM ITS PATH INTO DIFFERENT DIRECTIONS. |
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Term
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Definition
| ALTERNATING LIGHT AND DARK BANDS OF LIGHT THAT APPEAR TO FAN OUT FROM THE SUN'S POSITION, USUALLY AT TWILIGHT. |
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Term
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Definition
| THE BENDING OF LIGHT AS IT PASSES FROM ONE MEDIUM TO ANOTHER. |
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Term
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Definition
| THE APPARENT TWINKLING OF A STAR DUE TO ITS LIGHT PASSING THROUGH REGIONS OF DIFFERING AIR DENSITIES IN THE ATMOSPHERE. |
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Term
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Definition
| THE TIME AT THE BEGINNING OF THE DAY IMMEDIATELY BEFORE SUNRISE AND AT THE END OF THE DAY AFTER SUNSET WHEN THE SKY REMAINS ILLUMINATED. |
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Term
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Definition
| A SMALL GREEN COLOR THAT OCCASIONALLY APPEARS ON THE UPPER PART OF THE SUN AS IT RISES OR SETS. |
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Term
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Definition
| A REFRACTION PHENOMENON THAT MAKES AN OBJECT APPEAR TO BE DISPLACED FROM ITS TRUE POSITION. WHEN AN OBJECT APPEARS HIGHER THAN IT ACTUALLY IS, IT IS CALLED A SUPERIOR MIARAGE. WHEN AN OBJECT APPEARS LOWER THAN IT ACTUALLY IS, IT IS CALLED AN INFERIOR MIRAGE. |
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Term
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Definition
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Term
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Definition
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Term
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Definition
| RINGS OR ARCS THAT ENCIRCLE THE SUN OR MOON WHEN SEN THROUGH AN ICE CRYSTAL CLOUD OR A SKY FILLED WITH FALLING ICE CRYSTALS. HALOS ARE PRODUCED BY REFRACDTION OF LIGHT. |
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Term
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Definition
| AN ARC OF LIGHT TANGENT TO A HALO. IT FORMS BY REFRACTION OF LIGHT THROUGH ICE CRYSTALS. |
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Term
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Definition
| THE SEPARATION OF WHITE LIGHT INTO ITS DIFFERENT COMPONENT WAVELENGTHS. |
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Term
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Definition
| A COLORED LUMINOUS SPOT PRODUCED BY REFRACTION OF LIGHT THROUGH ICE CRYSTALS THAT APPEARS ON EITHER SIDE OF THE SUN. ALSO CALLED PARHELIA. |
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Term
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Definition
| A VERTICAL STREAK OF LIGHT EXTENDING ABOVE (OR BELOW) THE SUN. IT IS PRODUCED BY THE REFLECTION OF SUNLIGHT OFF ICE CRYSTALS. |
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Term
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Definition
| AN ARC OF CONCENTRIC BANDS THAT SPANS A SECTION OF THE SKY WHEN RAIN IS PRESENT AND THE SUN IS POSITIONED AT THE OBSERVER'S BACK. |
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Term
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Definition
| (OPTIC) A SERIES OF COLORED RINGS CONCENTRICALLY SURROUNDING THE DISK OF THE SUN OR MOON. SMALLER THAN THE HALO, THE CORONA IS OFTEN CAUSED BY THE DIFFRACTION OF LIGHT AROUND SMALL WATER DROPLETS OF UNIFORM SIZE. |
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Term
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Definition
| THE BENDING OF LIGHT AROUND OBJECTS, SUCH AS CLOUD AND FOG DROPLETS, PRODUCING FRINGES OF LIGHT AND DARK OR COLORED BANDS. |
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Term
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Definition
| BRILLIANT SPOTS OR BORDERS OF COLORS, MOST OFTEN RED AND GREEN, OBSERVED IN CLOUDS UP TO ABOUT 30 DEGREES FROM THE SUN. |
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