Weather Information Flashcards
State the general characteristics in regard to the flow of air around high and low pressure systems in the Northern Hemisphere.
Low pressure - inward, upward, and counter-clockwise
High pressure - outward, downward, and clockwise
If your route takes you towards a low-pressure system, in general, what kind of weather can you expect? What if you were flying towards a high-pressure system?
A low-pressure system is characterized by rising air, which causes cloudiness, precipitation and bad weather.
A high-pressure system is an area of descending air which tends to favor dissipation of cloudiness and good weather.
Describe the different types of fronts.
Acronym to remember: COWS
C - Cold Front - When mass of cold, dense, and stable air advances and replaces a body of warmer air. As it passes you may see; heavy rain, lightning, thunder/hail, tornadoes. Variable winds and gusting, poor visibility, temperature/dew point and barometric pressure drop rapidly.
O - Occluded Front - When a fast moving cold front catches up to a slow moving warm front.
W - Warm Front - When a warm air mass contacts and flows over a colder air mass. As it passes you may see; stratiform clouds, drizzle, low ceilings, poor visibility, variable winds, and rise in temperature.
S - Stationary Front - When two relatively equal air masses collide and remain in the same place for days. The resulting weather would be a mix of a cold and warm front.
What is a trough?
An elongated area of relatively low atmospheric pressure.
What is a ridge?
An elongated area of relatively high atmosphere pressure.
What are the standard temperature and pressure values for sea level?
59 F or 15 C and 29.92” Hg
What are isobars?
It is a line on a weather chart which connects areas of equal or constant barometric pressures.
If the isobars are relatively close together on a surface weather chart or a constant pressure chart, what information will this provide?
The spacing of isobars on these charts determine how steep or shallow a pressure gradient is. steep pressure gradient means fast winds while shallow pressure gradients means slower winds.
What is the name of the force that deflects winds to the right in the northern hemisphere and left in the southern hemisphere?
Coriolis force.
What is a METAR?
A METAR (Meteorological Aerodrome Report) is an hourly surface observation of conditions around an airport. There are two types of METARs - routine METARs that are transmitted every hour and SPECI which is issued to update the METAR whenever there are any significant changes in weather conditions.
What is a TAF?
A TAF (Terminal Area Forecast) is an aviation forecast of expected weather conditions at an airport. They are valid for 24 hours and issued 4 times a day.
What is an FA?
FA’s are issued for the Gulf of Mexico, the Caribbean Sea, and Alaska. Used to determine forecast enroute weather over a specific region. Cover an 18- to 24 hour period and issued 3-4 times daily depending on the region.
What is a Surface Analysis Chart?
These charts depicts the distribution of several items including sea level pressure, the position of highs, lows, ridges, troughs, fronts etc.
Produced 8 times daily.
What is a Radar Summary Chart?
Depicts precipitation types, cell movements, maximum echo tops, and locations of line echoes. Produced hourly.
What is a Winds and Temp Aloft Chart?
They are forecast prepared to help pilots in determining atmospheric conditions at various altitudes.
