Meteorology Flashcards
ISA
International Standard Atmosphere- 15 degrees Celsius and mean sea level. It is a model used for the standardization of aircraft instruments. It was established , with tables of values over a range of altitudes, to provide a common reference for temperature and pressure.
Standard Lapse Rate
ISA changes 2 degrees C per 1000’
Uneven heating of the Earths surface
Is the primary/basic cause of all weather on our planet. It is caused by the angle of the sun’s rays , and tilt of the Earth on its axis.
Cumulonimbus Clouds
Cloud type generally associated with thunderstorms. Large, towering (precipitating) cumulus clouds accompanied by thunder, lightning and rain. From a distance, the top of the cumulonimbus may look like a blacksmith’s anvil.
Lenticular Clouds
Form as a result of turbulence downwind of mountain ranges and exhibit a lens shape
Cirrus Clouds
Are the most common of the high clouds. They are composed of ice and are thin, wispy clouds blown in high winds into long streamers. Cirrus clouds are usually white and predict fair to pleasant weather.
Rotor Clouds
A turbulent cumuliform type of cloud that forms on the leeward side of large mountain ranges. The air in the cloud rotates about an axis parallel to the range.
Cumulus Clouds
Are white, puffy clouds that look like pieces of floating cotton. Cumulus clouds are often called “fair-weather clouds”. The base of each cloud is flat and the top of each cloud has rounded towers.
Stratus Clouds
Are uniform grayish clouds that often cover the entire sky. They resemble fog that doesn’t reach the ground. Light mist or drizzle sometimes falls out of these clouds.
3 Stages of a Thunderstorm
Cumulus, mature, dissipating
Adverse Weather phenomena that are associated with a thunderstorm
Rain, hail, updrafts, downdrafts, lightning, tornados
Advection fog
A fog formed when warm, moist air is blown over a cool surface
Radiation fog
Condensation of water vapor that results from the cooling of air that is in contact with the ground
Upslope fog
Fog created when air moves up a slope and cools adiabatically
Freezing fog
Fog formed in air that drops below freezing in which the water droplets become supercooled
Steam fog
Condensation of water vapor that results when cool air moves over warm water
Ice fog
In some areas where the ground temperatures drop below -29 degress Fahrenheit water vapor in the air near the surface turns into ice crystals that remain suspended in the air as fog
Rime Ice
Rime ice is an opaque, or milky white, deposit of ice that forms when the airplane is flying through filmy/stratiform clouds. It is dependent on a low rate of catch of small supercooled water droplets. It accumulates on the leading edges of wings and on antennas, pilot heads, etc.
Clear Ice
Clear ice or glaze ice is a heavy coating of glassy ice which forms when flying in areas with high concentration of large supercooled water droplets, such as cumuliform clouds and freezing rain.
Anticyclonic
A storms rotation that rotates in a clockwise direction in the northern hemisphere
Warm Front
Forms when a moist, warm air mass slides up and over a cold air mass. As the warm air mass rises, it condenses into a broad area of clouds. A warm front brings gentle rain or light snow, followed by warmer, milder weather.
Cold Front
Forms when a cold air mass pushes under a warm air mass, forcing the warm air to rise. Thunderheads can form as the moisture in the warm air mass rises, cools, and condenses. As the front moves through, cool, fair weather is likely to follow.
Stationary Front
Forms when warm and cold air meet and neither air mass has the force
to move the other. They remain stationary, or “standing still.” Where the warm and cold air meet, clouds and fog form, and it may rain or snow. Can bring many days of clouds and precipitation.
Occluded Front
Forms when a warm air mass gets caught between two cold air masses. The warm air mass rises as the cool air masses push and meet in the middle. The temperature drops as the warm air mass is occluded, or “cut off,” from the ground and pushed upward. Can bring strong winds and heavy precipitation.
Icing Conditions
10 degrees Celsius and visible moisture
Increase Stall speed and increase drag
Two things that icing can cause to happen to an aircraft that is in flight.
Increase head wind followed by a strong tail wind
Two things that help a pilot detect that they may be flying into a microburst
Ceiling
The lowest cloud layer of broken (BKN), overcast (OVC), or vertical visibility (VV) in a metar or TAF
METARs
Current meteorological report at an airport. Issued hourly, usually right before the top of the next hour. A typical METAR contains data for the temperature, dew point, wind direction and speed, precipitation, cloud cover and heights, visibility, and barometric pressure.
Speci Metar
Special METAR is an unscheduled Metar, issued in between the normal hourly reporting times if a significant change in weather conditions occurs.
TAF
Terminal Aerodrome Forecast - A forecast of weather conditions at a specific airport. TAFs are issued at least four times a day, every six hours, for major civil airfields: 0000z, 0600z, 1200z and 1800z, and generally apply to a 24 or 30-hour period
AMD TAF
Amended Terminal Aerodrome Forecast - an unscheduled TAF, issued in between the normal 6 hour reporting times if a forecasted significant change in weather conditions occurs.
Weather Observer
The purpose of a weather observer is to record weather conditions everyday at scheduled times
5 Required items to be reported in a METAR
Wind direction and speed, visibility, sky condition, temperature and dew point, and altimeter
PIREP
Pilot report of weather conditions encountered by aircraft in flight. PIREPS can be issued about turbulence, icing, winds, aircraft visibility and weather, low level wind shear, tops of storms or cloud layers. At a minimum the PIREP must contain a header, aircraft location, time, flight level, aircraft type and one other field stating the weather conditions encountered by the aircraft.
UA
Upper Air PIREP normal report
UUA
Urgent Upper Air PIREP
Surface Visibility Restrictions
Some of the meteorological conditions that may cause surface visibility restrictions include fog, snow, dust/sand, smoke, haze, and heavy rain.
Volcanic Ash
Dispatchers should avoid filing their planes on a route into or around volcanic ash. If volcanic ash is ingested into an engine the ash turns to a silica or glass. The silica adheres to the fan blades and other crucial parts of the engine causing it to fail
TEMPO
TEMPO is used for any conditions in wind, visibility, weather, or sky condition which are expected to last for generally less than an hour at a time (occasional), and are expected to occur during less than half the time period.
Conditional Language
Conditions which last less than half of the conditional timeframe
Ceiling
The lowest layer of clouds reported as being broken or overcast, or the vertical visibility into an obscuration like fog or haze.
SIGMENT
Significant Meteorological Information, A report issued to pilots that describe a potentially hazardous condition not normally issued in a forecast. Severe weather conditons. Sev turb, sev icing, widespread sandstorms/ Volcanic ash. Sigments are valid for 4 hours.
AIRMET
Airmen’s Meteorological Information, A report issued to pilots that describe a potentially hazardous condition not normally issued in a forecast. Light to Moderate in severity. Mod icing, mod turb, sustained surface winds greater than 30kt, mountain obscurations. Airments are valid for 6 hours
Convective Sigments
A report issued to pilots that describe a potentially hazardous severe convective area. Tornadoes, line of TS, embedded TS, hail greater than ¾ of an inch in diameter. Convective sigments are valid for 2 hours
Three ingredients of a Thunderstorm
Moisture, instability, and a lifting mechanism
IFR Conditions
Ceiling below 1,000ft
Visibility less than 3 SM
VFR Conditions
Ceiling greater than 3,000 ft and visibility greater than 5 statute miles; includes sky clear.
MVFR Conditions
Ceiling 1,000 to 3,000 feet and visibility 3-5 miles
CAT
Clear Air Turbulence, turbulence without any visual clues
LLWS
Low Level Wind Shear: when the wind rapidly changes in either direction or strength, common with thunder storms.
Contaminated Runway
A runway is contaminated when more than 25% of the runway surface is covered in more than 1/8 inch of a contaminate
