Ch. 3: Aviation Weather Sources & Effects

Question 1

Surface Aviation Weather Observations

Answer 1

network made up of government and

privately contracted facilities that provide continuous up-to-date weather information

Question 2

METAR

Answer 2

an observation of current surface weather reported in a standard international format

Question 3

What 12 items are included in the standard internation format for METARs?

Answer 3

type of report
station identifier
date/time
modifier
wind
visibility
weather
sky condition, temperature/dew point
altimeter setting
zulu time
remarks

Question 4

Terminal Aerodrome Forecasts (TAF)

Answer 4

a report established for the five statute mile radius around an airport

usually given for larger airports

valid for 24 or 30-hour time period

updated 4 times a day

Question 5

What 10 items are included in a TAF?

Answer 5

type of report
station identifier
date/time of origin
valid period dates/time
forecast wind
forecast visibility
forecast significant weather
forecast sky condition
forecast change group 
PROB30

Question 6

What is PROB30?

Answer 6

a given percentage that describes the probability of thunderstorms and
precipitation occurring in the coming hours

Question 7

Convective Significant Meteorological Information (WST)

Answer 7

issued for severe thunderstorms with surface winds greater than 50 knots, hail
at the surface greater than or equal to ¾ inch in diameter, or tornadoes

Question 8

Density Altitude

Answer 8

the altitude in the standard atmosphere corresponding to a particular value of air
density

Question 9

As the density of the air increases (lower density altitude), what happens to aircraft performance?

Answer 9

Increases.

Question 10

As air density decreases (higher density altitude), what happens to aircraft performance?

Answer 10

Decreases.

Question 11

What factor affect air density?

Answer 11

Changes in altitude, temperature, and humidity.

Question 12

High density altitude refers to what?

Answer 12

Thin air.

Question 13

Low density altitude refers to what?

Answer 13

Dense air.

Question 14

What conditions result in a high density altitude?

Answer 14

High elevations
Low atmospheric pressures
High temperatures
High humidity
Combination of these factors

Question 15

What conditions are more indicative of a low density altitude?

Answer 15

Lower elevations
High atmospheric pressure
Low temperatures
Low humidity

Question 16

What affect does pressure have on density?

Answer 16

As pressure increases, density increases. As pressure decreases, density decreases.

Question 17

What affect does temperature have on density?

Answer 17

As temperature increases, density decreases. As temperature decreases, density increases.

Question 18

True or False: In the atmosphere, temperature increases and pressure decreases with altitude.

Answer 18

False. Both temperature and pressure decrease with altitude.

Question 19

Humidity

Answer 19

the amount of water vapor contained in the

atmosphere

Question 20

True of false: Warm air can hold more water vapor, while cold air can hold less.

Answer 20

True.

Question 21

What affect does humidity/moisture have on density?

Answer 21

As the water content of the air increases, the air becomes less dense, increasing
density altitude and decreasing performance.