Weather Flashcards
What is a dryline, and why is it important to know its location?
- Low-level boundary hundreds of miles long
- Usually north-south across southern and central high plains in spring and early summer. Separates the Gulf of Mexico to the east and dry desert air from the southwest states to the west
- Sever tornado thunderstorms often develop along dryline
What meteorological conditions should you be aware of to avoid icing in flight?
- Fronts: It’s location, type, speed & direction of movement
- Clouds: To determine whether you can climb through or descend below to warmer temperatures
- Freezing Levels: Important to know to avoid freezing levels, and how and where to go to exit/avoid
- Temps & Pressure: Icing tends to be found around low pressure areas & temps at/around freezing
- Precipitation: Helpful to avoid visible moisture and areas conducive to severe icing
What are factors necessary for a TS to form, and what are the 3 stages for TS development?
- TS formation must have: sufficient water vapor, unstable lapse rate, lifting force to start the storm process in motion
Stage 1: Cumulus (updrafts)
Stage 2: Mature (precipitation reaches the surface; precip descends through cloud and drags adjacent air downward
Stage 3: Dissipating: Downdrafts characterize the dissipating stage and storm dies rapidly
Explain “squall line” TS:
- Non-frontal narrow band of active TS
- Develops ahead of cold front in moist unstable air
- Line may be too long and wide to detour around
How is hail vs. freezing rain differ?
- Freezing rain is water droplets that freeze as they’re falling to the surface
- Hail is freezing rain, but there’s a lifting form present that’s strong enough to lift up the freezing rain. Eventually when it’s heavy enough to penetrate the lifting force, it falls to the surface. The size of the hail depends on the amount of lifting force
How many types of inflight aviation weather advisories are there?
- SIGMETs
- Convective SIGMETs
- AIRMET
- Center Weather Advisory
AIRMETs & SIGMET’s are considered widespread because they cover how large of an area?
- 3,000 square miles at any one time
How long are SIGMETs valid for?
- 4 hours
- 6 hours if associated with tropical cyclones and volcanic ash clouds
What are some examples of SIGMETs?
- Severe icing not associated with TS
- Severe or extreme turbulence not associated w/ TS
- Dust Storms reducing vis. to less than 3 miles
Volcanic ash
in AS and HI
- Tornadoes
- Lines of TS
- Squall lines
- Haile greater than 3/4”
What alphanumeric designators is issued with regards to SIGMETs?
- Similar to ATIS, it used November through Yankee, but excludes Sierra & Tango (as used in AIRMETs)
-
What are the weather conditions that dictate VFR, MVFR, IFR and LIFR?
VFR: Greater than 3,000’ & more than 5 miles vis
MVFR: 1,000’ - 3,000’ ceiling & 3-5 miles vis
IFR: 500’ - 1,000’ ceilings & 1 to less than 3 miles vis
LIFR: Less than 500’ ceilings & less than 1 mile visibility
At what temperatures can a pilot expect icing?
Temps between 2° and -10° celcius
What are the different categories (not type) of icing?
Trace: Ice accumulation is slightly greater than the rate of sublimation (melting). Can be an issue if in prolonged conditions for more than an hour.
Light: Requires occasional use of deicing equipment can remove icing. Prolonged for too long may cause hazardous conditions.
Moderate: Short encounters become potentially hazardous. Use of deicing equipment or flight diversion may be necessary
Severe:
What are the different categories (not type) of icing?
Trace: Ice accumulation is slightly greater than the rate of sublimation (melting). Can be an issue if in prolonged conditions for more than an hour.
Light: Requires occasional use of deicing equipment can remove icing. Prolonged for too long may cause hazardous conditions.
Moderate: Short encounters become potentially hazardous. Use of deicing equipment or flight diversion may be necessary
Severe: The rate of ice accumulation is so severe that deicing equipment cannot remove icing conditions. A diversion is necessary.
First sign of performance degradation due to ice is?
- An increase in drag. You would observe this when more power is required than normal for cruise performance.
- Because of the increase in drag, a decrease in climb performance is now an issue.
