Term
| Describe characteristics of the Troposphere |
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Definition
| From surface to anywhere between 28-55K. Average 36K top over CONUS. Temperature decreases with increasing altitude. Nearly all weather occurs here. Winds increase with altitude. |
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Term
| Describe characteristics of the Tropopause |
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Definition
| Boundary between troposphere and stratosphere (transition zone). Constant temp with altitude increase (-56.5 C). Jet stream occurs just below. Contrails form near it. Avg height 36,000' MSL |
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Term
| Describe characteristics of the Stratosphere |
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Definition
| Increasing temp with increasing altitude due to ozone. Outstanding flying; smooth with excellent visibility. Lack of weather. |
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Term
| Describe flight conditions associated with the Troposphere |
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Definition
| Winds are light generally, weather occurs here. Standard lapse rate applies. Jet stream turbulence near top boundary. |
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Term
| Describe flight conditions associated with the Tropopause |
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Definition
| Jet stream just below, wind shear. Thunderstorms may penetrate the top, otherwise generally clear. Haze layer with definite top often exists |
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Term
| Describe flight conditions associated with the Stratosphere |
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Definition
| Outstanding. Free of weather (besides very top of anvils). Thin air with little resistance to aircraft motion. |
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Term
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Definition
| Decreasing atmospheric temperature with increasing altitude. Can be constant or inverted. |
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Term
| State the average lapse rate |
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Definition
| Standard is 2 C or 3.57 F/1,000 feet. |
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Term
| Define atmospheric pressure |
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Definition
| Pressure exerted on a surface by the atmosphere due to the weight of the column of air directly above that surface (standard conditions 14.7 psi) |
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Term
| State standard units of pressure measurement |
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Definition
| inches of Mercury (inHg) and millibars (mb). usual varies from about 28 inHg to 31 inHg (960-1060 mb) |
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Term
| Define the standard atmosphere |
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Definition
| 29.92 inHg (1013.25 mb), 15 C (59 F), pressure lapse rate 1 inHg/1,000' altitude (34 mb), 2 C/1,000' altitude (3.57 F) |
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Term
| Differentiate between sea level pressure and station pressure |
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Definition
| SLP is pressure at actual sea level or what it would be with standard pressure lapse rate based on actual conditions. Station pressure is actual pressure at that station. |
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Term
| Define types of altitudes |
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Definition
Indicated - shown on altimeter. Determined from static port
Calibrated - Adjusted for instrument/installation error
MSL - height above sea level
AGL - height above terrain
Pressure - height above standard datum plane (actual 29.92 inHg level)
Density - corrected for non-standard temperature. Not real measure of altitude, used for performance. |
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Term
| Define indicated altitude |
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Definition
| value shown on altimeter. adjusted for Kollsman window setting |
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Term
| Describe effects of pressure changes on aircraft altimeters |
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Definition
| as pressure increases without adjusting Kollsman window setting, indicated is lower than actual (plane is higher than altimeter says it is). reverse holds true |
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Term
| Describe effects of temperature deviations from standard lapse rate on aircraft altimeters |
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Definition
| increase in temperature (or slower lapse rate) causes air to be less dense. higher temperature cause indicated to be lower than actual (plane actually higher than what is indicated). Reverse holds true for faster lapse rate |
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Term
| Explain the term pressure gradient |
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Definition
| the difference in pressures between two areas. Wind tends to flow from high to low (positive pressure gradient). Initiating force for all winds |
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Term
| Explain and identify gradient winds |
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Definition
| Above 2,000' AGL, flow parallel to isobars due to coriolis effect |
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Term
| Explain and identify Buys Ballot's Law w.r.t. isobars around pressure systems in the Northern Hemisphere |
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Definition
| If the wind is at your back, area of low pressure will be to your left. When standing on Earth's surface, low will be slightly forward or directly left because the winds flow across the isobars |
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Term
| Explain and identify surface wind direction w.r.t. gradient winds in a pressure system in the Northern Hemisphere |
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Definition
| surface winds blow approximately 45 degrees outward across pressure gradients, CCW around high pressure, CW around low. Turned by coriolis force but not as much. |
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Term
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Definition
| Below the tropopause. winds in excess of 250 kts. 3000-7000' thick, 1000-3000 mile segments, 100-400 miles wide. Steeper difference in wind speed as you go in vertically vs. horizontally. |
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Term
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Definition
| Cool, dense air blows in from over water (higher pressure) to warmer, low pressure over land. Happens during day. 15-20kts |
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Term
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Definition
| Land cools off, air begins to thicken. Blows over the water which is heated/holding heat and lower pressure. Slightly weaker than sea breezes |
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Term
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Definition
| at night, air along mountain slope is cooled, becoming denser. flows down the mountain slope and pushes up warm air in middle |
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Term
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Definition
| mountain slope heated, air begins to rise. Cools while moving away from warm ground, settling down toward the valley floor. |
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Term
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Definition
| The point at which air can hold no more water |
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Term
| Define dew point temperature |
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Definition
| the temperature which the air would have to cool in order to become completely saturated. |
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Term
| Define dew point depression/spread |
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Definition
| The difference between temperature and dew point |
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Term
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Definition
| The percent of saturation of the air |
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Term
| Describe the relationship between air temperature and dew point temperature w.r.t. saturation |
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Definition
| the more the air cools relative to the dew point, the more saturated the air becomes. vice versa. |
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Term
| Describe Showery precipitation |
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Definition
| characterized by sudden beginning and ending, and abruptly changing intensity/sky conditions. Showers are associated with cumuliform clouds |
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Term
| List the three characteristics of precipitation |
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Definition
| Showers, Continuous, Intermittent |
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Term
| Describe Continuous precipitation |
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Definition
| AKA steady or not showery. Intensity changes gradually, if at all. Associated with stratiform clouds |
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Term
| Describe Intermittent precipitation |
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Definition
| Stops and restarts at once during the hour. Can be either showery or steady, so either cumuliform or stratiform clouds. |
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Term
| List the types of precipitation |
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Definition
| Rain, Hail/grauple, Snow, Drizzle, Freezing Drizzle, Freezing Rain, Ice pellets/sleet, snow grains |
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Term
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Definition
| Precipitation in form of water droplets that are larger than drizzle and fall to the ground |
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Term
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Definition
| composed of irregular lumps of ice that develop in severe thunderstorms, consisting of alternate opaque and clear layers of ice in most cases |
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Term
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Definition
| Very small droplets of water that appear to float in the atmosphere |
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Term
| Describe Freezing Drizzle |
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Definition
| Drizzle that freezes on impact with objects |
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Term
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Definition
| Rain that freezes on impact with objects |
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Term
| Describe Ice pellets/Sleet |
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Definition
| Small translucent and irregularly shaped particles of ice. Form when rain falls through air with temperatures below freezing. Usually bounce when hitting ground and make a noise on impact. Does not cause structural icing. |
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Term
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Definition
| White or translucent ice crystals. Created when condensation takes place at temperatures less than freezing, so water vapor changes directly into minute ice crystals. Wet snow (partially melted) can cause structural icing |
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Term
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Definition
| very small white, opaque grains of ice. When grains hit the ground, they do not bounce or shatter. Usually fall in small quantities from stratus-type clouds, never as showers |
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Term
| List the four principal cloud groups |
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Definition
| Low, Middle, High and Special |
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Term
| Describe Low clouds and weather associated |
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Definition
| just above surface - 6,500' AGL. varied turbulence none to moderate. Generally light rain or drizzle (or none). Mainly composed of water droplets. |
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Term
| Describe middle clouds and weather associated |
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Definition
| 6,500'-20,000' AGL. Composed of ice crystals, water droplets or a mixture. Prefix alto-. Rain, Rain/snow, or snow can be encountered if they are thick. Virga can also happen. |
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Term
| Describe High clouds and weather associated |
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Definition
| above 20,000' AGL. little effect on flying except for turbulence and visibility issues with jet stream. too high/cold to present an icing hazard. No precipitation. |
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Term
| Describe special clouds and weather associated |
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Definition
| extensive vertical development (don't fall into just one category) suffix/prefix "nimbus." Generally means rain/storms. Nimbostratus - continuous rain, snow or ice pellets. Cumulonimbus - thunderstorms. Towering cumulus are almost thunderstorms. |
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Term
| Describe the types of atmospheric stability |
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Definition
Stable - tends to return to original position
Neutrally stable - doesn't return to original position, but stays put after initial displacement
Unstable - once displaced, continues to move away from initial position never to return |
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Term
| Describe the four methods of lifting |
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Definition
Frontal - a cold front pushes up the warmer air of a warmer airmass that it displaces.
Orographic - air is displaced upward by a mountainside
Convergence - two airmasses converging causes air to be forced upward (nowhere to go but up)
Thermal - cool air is passed over a warm surface. Intensified by solar heating. |
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Term
| Describe the flight conditions associated with a stable atmosphere |
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Definition
Front - warm
Airmass - warm
Turbulence - smooth
Visibility - poor
Icing - rime
Precipitation - steady
Winds - steady
Clouds - stratiform |
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Term
| Describe the flight conditions associated with an unstable atmosphere |
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Definition
Front - cold
Airmass - cold
Turbulence - rough
Visibility - clear outside clouds
Icing - clear
Precipitation - showery
Winds - gusty
Clouds - cumuliform |
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Term
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Definition
| a large body of air that has essentially uniform temperature and moisture conditions in a horizontal plane. May vary in size from several hundred to more than several thousand square miles. |
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Term
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Definition
| An area of discontinuity that forms between two contrasting air masses when they are adjacent to each other. The boundary of an airmass colliding with another; change in temperature/pressure/winds/etc. Always found in a low pressure trough. |
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Term
| Describe the structure of a front |
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Definition
| Can be hundreds of miles long. Three-dimensional. Point where it comes in contact with ground is called surface front |
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Term
| Describe the discontinuities used to locate and classify fronts |
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Definition
| low pressure trough. shift in winds, temperature, and pressure, moisture |
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Term
| Describe the factors that influence frontal weather |
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Definition
Moisture available
Contrast temperature/moisture
Stability of lifted air
Slope of front
Speed of front |
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Term
| Describe the conditions associated with a cold front |
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Definition
| cold air pushing up warmer air. Southwesterly winds ahead switch to NW. front moves NW - SE. precipitation and winds pick up as it passes. unstable and sometimes violent conditions. weather is in a narrow band. |
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Term
| Describe the characteristics of a squall line |
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Definition
| line of violent thunderstorms. develop 50 - 300 miles ahead of a cold front and parallel. form when cold air downdrafts ahead of a cold front lift additional unstable air. 90 degree wind shift from SW to NW |
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Term
| describe the characteristics of a warm front |
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Definition
| slower speed - 15 knots. winds shift SE to SW. accompanied by low stratus and fog. precipitation raises moisture content of cold air, saturation point can be reached. thunderstorms can be embedded if warm air is moist. steady precipitation if any. |
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Term
| describe the conditions associated with a stationary front |
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Definition
| two fronts up against each other with weak forces behind them; neither overtakes the other. Winds tend to blow parallel and opposite on either side. Similar to warm front conditions but less intense. |
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Term
| describe conditions associated with occluded fronts |
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Definition
| Faster moving cold front overtakes a warm front. Warm type and cold type. weather is a combination of both types of frontal weather. Moth severe weather occurs 100NM south to 300NM north of the frontal intersection |
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Term
| Describe conditions associated with an inactive front |
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Definition
| any front that is too dry to produce weather. Still has change in temperature, pressure and winds |
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Term
| List the classifications of turbulence used in Pilot Reports |
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Definition
| wind shear, thermal/convective, frontal, mechanical |
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Term
| List the intensities of turbulence used in Pilot Reports |
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Definition
| Light, Moderate, Severe, Extreme |
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Term
| Define the terms used to report turbulence with respect to time |
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Definition
| occasional, intermittent, continuous |
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Term
| Describe the use of surface analysis charts |
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Definition
| used to see past fronts, high and low pressure, isobars, etc. fifteen-thirty minutes old information (not current) but shows trends |
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Term
| Describe the use of Low Level Significant Weather Prognostic Charts |
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Definition
| Forecast prog charts - 12, 24, 36 and 48 hours out. Isobars are 4mb apart |
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Term
| Describe displayed data METARs |
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Definition
| Current weather taken 55-59 minutes after the hour. winds, temperature, dewpoint, visibility, type of weather. Also can be SPECI, or special report when necessary, outside of regular METARs |
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Term
| Describe weather data on NEXRAD |
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Definition
| Shows the intensity of the light bouncing off the radar. Means more clouds, etc. more light. Can indirectly determine hail, tornadoes, microbursts, and wind shear |
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Term
| Describe weather data on satellite imagery |
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Definition
| clouds show as white. only works during the day (no light to reflect during night). Two types: visual and infrared. Infrared works at night, returns temp differences between cloud tops and ground |
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Term
| Describe use of Winds-Aloft Prognostic Charts |
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Definition
| View winds forecast at different altitudes/flight levels. |
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Term
| Describe use of Winds-Aloft Forecasts |
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Definition
| read for the areas you're passing through. choose appropriate tailwind and headwind, along with other considerations. |
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Term
| Describe use of Severe Weather Watch |
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Definition
Identified by "WW" in heading. As required. Given in local time. Issued for Funnel clouds/tornadoes OR Severe Thunderstorms - lightning with 50kts or greater wind or 3/4 inch diameter hail.
In teletype format |
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Term
| Describe use of in-flight weather advisories |
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Definition
Airmets - good for 6 hours. significant weather phenomena, lower intensities than SIGMETs. Sierra - visibility. Tango - turbulence. Zulu - icing. Can reference SIGMETs if related.
Sigmets - severe weather other than thunderstorms/convection. turbulence, icing, dust storms, ash clouds. good for four hours
convective sigmets - thunderstorms. good for two hours. Tornadoes, lines and embedded thunderstorms. hail 3/4" and/or 50kt wind excess. |
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Term
| State the letter identifiers of in-flight weather advisories |
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Definition
AIRMET - WA
Convective SIGMET - WST
SIGMET - WS (UWS for urgent pre-sigmet)
Severe Weather Watch - WW
Severe Weather Forecast Alert - AWW (preliminary for WW) |
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Term
| Describe the use of PIREPs |
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Definition
Required when requested by tower. They will request when ceilings under 5,000 or visibility less than 5SM, or thunderstorms, light icing, moderate turbulence, and wind shear.
Required to submit PIREP when: unusual/unforecast conditions, IFR approach conditions different than last observation, missed approach due to weather or with wind shear on departure/arrival |
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Term
| Describe the weather data entered on a DD-175-1 |
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Definition
| info along flight. runway conditions, temperature, pressure and density altitudes, surface winds, clim b winds, weather advisories and watches, winds aloft at flight level, clouds or visibility at desired flight level, freezing level, cloud tops, thunderstorms predicted. NEED initials and Flimsy code. Cloud layers, |
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Term
| Describe differences in US civil, military and international TAFs |
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Definition
US civil stations use statute miles, military use meters.
US Civil include date time group of transmission prior to forecast period (military assumes it's a recent forecast)
US Military TAFs amend/correct/delay forecast add a remark with AMD time
US Civil may include probability of precipitation in TAF
International has variable forecast period; US Military is 24 hours
INTL may use knots, meters or kph. Military uses knots for WS
CAVOK potential |
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