Weather Flashcards
In general, what weather can you expect in a high pressure system?
A high pressure system is an area of descending air, which tends to favor dissipation of cloudiness and good weather.
What is the flow of air around high pressure systems in the northern hemisphere?
Outward, downward, clockwise.
What are the general characteristics of the weather near a cold front?
As the front passes expect towering cumulus or cumulonimbus clouds, heavy rain, lightning, thunder and hail, poor visibility. Winds could be variable and gusting. Temp/dew point/pressure drop rapidly.
What are the different precipitation types?
Drizzle, rain, freezing rain, freezing drizzle, snow, snow grains, ice crystals, ice pellets, hail, small hail, snow pellets
What are the 3 primary causes of turbulence?
Convective currents
Obstructions in the wind
Wind sheer
What is the flow of air around a low pressure system in the northern hemisphere?
Inward, upward, counterclockwise
What are the general characteristics of the weather near a warm front?
As the front passes, expect weather, stratiform clouds, drizzle, low ceilings poor visibility, variable winds and a rise in temp.
4 levels of turbulence
Light
Moderate
Severe
Extreme
What is a Convective SIGMET?
Thunderstorms
Squall Lines
Hail
What are the three types of AIRMETs?
Sierra- visibility
Tango- turbulence
Zulu- icing
High level clouds above 20,000 ft, fibrous, wispy.
Cirrus
Rime Ice
Opaque appearance
formed in stratus clouds
results from instantaneous freezing of tiny super cooled water striking an aircraft surface
-15 C to -20 C
Which thunderstorms produce the most intense hazards to aircraft?
Squall line thunderstorms
Lower Clouds 6,500 ft and below
Stratus
Ice Fog
In cold weather when the temp is much below freezing and water forms directly into ice crystals.
What would decrease the stability of an air mass?
Warming from below
When the term light and variable is used in reference to winds aloft the coded group and wind speed is…
9900 and less than 5 knots
A pilot can expect a wind-sheer zone in a temperature inversion whenever the wind speed at 2,000 - 4,000 AGL is at least…
25 knots
What is standard pressure
29.92 in
What is standard temperature in Celsius?
15 C
The wind condition that requires maximum caution when avoiding wake turbulence on landing is
light quartly tailwind.
What is Inversion
Shallow layers of smooth stable air close to the ground . Warm area above keeping air trapped.
What is atmospheric stability
The stability of atmosphere is the ability to resist vertical motion
Cold Front
Dense mass of air, stays close to the surface. Advances quickly.
Air cools _____ Celsius per 1000 ft of Alt. gained
2 degrees Celsius
Moist Stable air flowing upslope can be expected to form…
stratus type clouds.
Radiation Fog
Forms when the ground cools rapidly due to terrestrial radiation, and surrounding air reaches dew point.
Steam Fog
When cold dry air moves over warm water.
What is a METAR.
An hourly surface observations of conditions observed at an airport.
In general what weather can you expect in a low pressure system.
A low-pressure system is a system characterized by rising air which is conducive to cloudiness, precipitation, and bad weather.
What are convective currents?
Uneven heating of air creates areas of local circulation.
Coriolis Force
The force created by the rotation of the Earth.
Warm Front
warm mass of air advancing high humidity
shown by red lines
Deviation
Obtained from deviation card in the aircraft. Created form magnetic fields in the aircraft.
CAT
Clear Air Turbulence
sudden, severe, in cloudless regions
High Alt, above 15,000 MSL
Class Charlie Alt/Size
4000 AGL
Bottom ring extends 5nm from airport.
Upper ring from 1200 AGL to 4000, 10nm from airport.
Mixed Ice
Mix of Clear and Rime Ice
-10 C and -15 C
Which way does air deflect in Northern Hemisphere?
Deflects to the right.
SIGMET
Advises of weather that is potentially hazardous to all aircraft. They are unscheduled and are valid for 4 hrs.
What are TAFs
Terminal aerodrome forecast is a concise statement of the expected meteorological conditions for a specified time period within 5 statute miles of airport center.
3 types of Icing
Structural, Induction, instrumental icing
3 stages of a Thunderstorm
1) Cumulus stage
2) Mature stage (moisture begins falling most dangerous stage)
3) Dissipating stage (downdrafts spread out)
Upslope Fog
Moist stable air is forced up sloping land like mountains
What is a PIREP
A PIREP is a pilot report regarding conditions as they exist in the air.
METAR Decode
1) Type of report
2) ICAO station identifier
3) Date and time of report
4) Modifier (auto if auto generated)
5) Wind
6) Visibility
7) Runway visual range
8) Weather phenomena
9) Sky condition
10) Temperature
11) Altimeter
12) Remarks
Describe several types of weather observing programs
Manual observations
AWOS- automated weather observing system
ASOS- Automated surface observing system
What service does the FAA provide for pilots to obtain a weather briefing
FAA provides the Flight Service program which provides weather briefings to pilots through it’s Flight Service Stations by phone 1-800-WX-BRIEF and online at 1800wxbrief.com
Cumulus Clouds
heaped or piled clouds
Cirrus Clouds
ringlets, fibrous, high level 20,000 AGL +
Cumulonimbus Clouds
Signs of thunderstorms, squall lines, unstable air
Nimbus Clouds
Rain bearing clouds
Stratus
Formed in layers 6500 AGL and below.
How heavy is the Atmosphere at sea level
14.7 lbs/ in2
supports 29.92 inches of mercury
On average, with every 1000 ft of increase of Alt. the atmosphere pressure decrease of…
decrease 1” of Mercury.
Squall Line
A narrow band of active T-storms.
The amount of moisture in the air depends on what factor
Every 20 degrees increase in temp. doubles amount of moisture the air can hold.
Advection Fog
Common in coastal areas. When a layer of warm moist air moves over a cold surface.
Wind Shear
A sudden drastic change in wind speed or direction over a very small area.
Clear Ice
Develope in cumulus clouds or freezing rain. Flows over surface and slowly freezes creating a glaze.
What type of briefings are available from a FSS briefer
Standard brief
Abbreviated brief
Outlook brief
Inflight brief
What is an AIRMET?
A textual advisory of significant weather that is less severe than SIGMETs.
What is a G-AIRMET
A graphical advisory that may be hazardous but is less severe than a SIGMET. Issued 3 hrs apart for 12 hours into the future.
