Weather

Question 1

What is a dryline, and why is it important to know its location?

Answer 1

• 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

Question 2

What meteorological conditions should you be aware of to avoid icing in flight?

Answer 2

1. Fronts: It’s location, type, speed & direction of movement
2. Clouds: To determine whether you can climb through or descend below to warmer temperatures
3. Freezing Levels: Important to know to avoid freezing levels, and how and where to go to exit/avoid
4. Temps & Pressure: Icing tends to be found around low pressure areas & temps at/around freezing
5. Precipitation: Helpful to avoid visible moisture and areas conducive to severe icing

Question 3

What are factors necessary for a TS to form, and what are the 3 stages for TS development?

Answer 3

• 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

Question 4

Explain “squall line” TS:

Answer 4

• 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

Question 5

How is hail vs. freezing rain differ?

Answer 5

• 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

Question 6

How many types of inflight aviation weather advisories are there?

Answer 6

1. SIGMETs
2. Convective SIGMETs
3. AIRMET
4. Center Weather Advisory

Question 7

AIRMETs & SIGMET’s are considered widespread because they cover how large of an area?

Answer 7

• 3,000 square miles at any one time

Question 8

How long are SIGMETs valid for?

Answer 8

• 4 hours
• 6 hours if associated with tropical cyclones and volcanic ash clouds

Question 9

What are some examples of SIGMETs?

Answer 9

• 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”

Question 10

What alphanumeric designators is issued with regards to SIGMETs?

Answer 10

• Similar to ATIS, it used November through Yankee, but excludes Sierra & Tango (as used in AIRMETs)

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Question 11

What are the weather conditions that dictate VFR, MVFR, IFR and LIFR?

Answer 11

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

Question 12

At what temperatures can a pilot expect icing?

Answer 12

Temps between 2° and -10° celcius

Question 13

What are the different categories (not type) of icing?

Answer 13

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:

Question 13

What are the different categories (not type) of icing?

Answer 13

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.

Question 14

First sign of performance degradation due to ice is?

Answer 14

• 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.

Question 15

What configuration is required for a tail stall to occur?

Answer 15

• Full flaps or near full flaps setting is required to induce a tail stall

Question 16

All weather occurs in which part of the earth’s atmosphere?

Answer 16

Troposphere

Question 17

What determines the vertical depth of the troposphere?

Answer 17

• The height is determined by season and latitude
• It’s higher in the summer and lower in the winter
• 11 to 12 miles (

Question 18

Regarding constant pressure charts, what altitude is 200 millibars (5”Hg) located?

Answer 18

39,000’ but ranges between 35,000 to 41,000’

Question 19

Which constant pressure chart level is used primarily to locate jetstreams?

Answer 19

200 mb & 300 mb charts

Question 20

How can we locate shortwaves using the 500 mb constant pressure chart?

Answer 20

• Find the vorticity maximum number using the filter on the map
• The higher the number, the higher the vorticity (planetary, curvature, and shear vorticity)

Question 21

The 700 mb constant pressure chart gives us a picture of:

Answer 21

• Relative humidity and shows where there’s vertical motion with the use of the omega sign
• We can forecast where weather is going to be developing

Question 22

What is the definition of a ceiling?

Answer 22

The lowest level of obscuration AGL covering more than 5/8th of the sky. Either broken or overcast.