A107

Question 1

An air mass moving over a warm surface and is heated from below (convective heating) creates what effects?

Answer 1

Unstable air and turbulence

Question 2

Warm fronts cause what type of precipitation?

Answer 2

Light to moderate precipitation

Question 3

Warm fronts likely cause what type of clouds?

Answer 3

Blanket-type (stratus) clouds

Question 4

What type of effect does an air mass passing over a cold surface create?

Answer 4

Creates a stable air mass with poor visibility

Question 5

At what speed do cold fronts move?

Answer 5

Rapidly

Question 6

Which front stays close to the ground?

Answer 6

Cold front

Question 7

What kind of clouds are created from cold fronts?

Answer 7

Towering cumulus and cumulonimbus

Question 8

What type of weather/precipitation is associated with cold fronts?

Answer 8

Severe weather with extreme precipitation

Question 9

What three things must be present for clouds?

Answer 9

Adequate water vapor
Condensation nuclei (dust particle to cling to)
Air to cool to reach its saturation pointx

Question 10

Define low clouds

Answer 10

Surface to 6500, mostly water droplets (fog included)

Question 11

Define middle clouds

Answer 11

6500-20000
Composed of water, ice crystals, and supercooled water droplets
Can produce turbulence and moderate icing

Question 12

Define high clouds

Answer 12

Above 20,000
Composed of ice crystals
Form in stable air

Question 13

What is a major factor in circulation of air?

Answer 13

Uneven heating of the earth’s surface

Question 14

where is the troposphere?

Answer 14

From sea level to 20,000-48,000 (poles and equator, respectively)

Question 15

What is the tropopause?

Answer 15

Top layer of troposphere—there is turbulence here

Question 16

What is the Coriolis effect?

Answer 16

Causes deflection to right in northern hemisphere and deflection to left in Southern Hemisphere

Question 17

What happens in unstable air?

Answer 17

Small vertical air movements tend to become larger

Generates turbulence and convective weather

Question 18

What is temperature inversion?

Answer 18

Air gets warmer as temperature increases (to a certain point)
The layer at the top acts as a lid—traps pollution, haze, smoke—can result in decreased visibility

Question 19

What happens in stable air?

Answer 19

Makes vertical movement difficult; sometimes associated with temp inversion

Question 20

What hazards to aviation may be present from thunderstorms?

Answer 20

Updrafts/downdrafts, large hail stones, lightning, tornadoes, windshear, severe turbulence

Question 21

Define windshear

Answer 21

A sudden, drastic change in wind speed or direction

Question 22

What commonly causes windshear?

Answer 22

Passing frontal systems, thunderstorms,

temperature inversion, and surface obstruction

Question 23

Define microburst

Answer 23

A critical type of shear

Typically has diameter of 1-2 miles

Usually 15 min lifespan

Downdrafts up to 6,000ft/min

Question 24

What is a METAR

Answer 24

Hourly observed weather report

Question 25

When is a METAR observed?

Answer 25

45min to top of the hour

Question 26

When is a METAR reported?

Answer 26

50 min to top of the hour

Question 27

How far from an airfield does a METAR include weather info for?

Answer 27

5 miles

Question 28

If a METAR says “VC” what does this mean?

Answer 28

In the vicinity—5-10 miles

Question 29

What does DSNT mean on a METAR?

Answer 29

Distant—greater than 10 mikes

Question 30

What are the five levels of cloud coverage?

Answer 30

``` Skc—sky clear Few—1-2/8 Sct—3-4/8 Bkn—5-7/8 Ovc—8/8 ```

Question 31

What is a TAF?

Answer 31

A weather forecast

Question 32

What type of weather can be expected from moist, unstable air and very warm surface temperature?

Answer 32

Strong updrafts and cumulus clouds

Question 33

What are the three stages of a thunderstorm?

Answer 33

1. cumulus stage: lifting action begins, needs moisture and instability 2. Mature stage: most violent time, precipitation begins to fall 3. Disappearing stage: downdrafts spread out, lifting action stop

Question 34

What happens if a wind shear causes a headwind to change to a tailwind?

Answer 34

Loss of aircraft performance

Question 35

What is prevailing visability?

Answer 35

The greatest horizontal visibility observed through at least half the horizon circle and is not not necessarily continuous

Question 36

How long is a routine TAF valid?

Answer 36

24 hours