Weather

Question 1

International Standard Atmosphere (ISA)

Answer 1

15º C

Question 2

Dry Adiabatic Lapse Rate

Answer 2

2º C / 1000 ft

Question 3

AIRMET Issue Times

Answer 3

AIRMETs are issued four times per day at 0245Z, 0845Z, 1445Z, and 2045Z. They are also issued on an unscheduled basis when weather conditions are occurring or expected to occur, but weren’t forecast.

Question 4

AIRMET Valid Times

Answer 4

AIRMETs are valid up to 6 hours; however, AIRMETs may contain remarks about the continuance of weather during the 6 hours following the AIRMET end time.

Finally, AIRMETs can also contain a separate outlook when conditions are expected to occur during the 6 hour period after the AIRMET end time.

Question 5

Types of AIRMETS and Issuance Criteria

Answer 5

AIRMET SIERRA (IFR or mountain obscuration)
Ceilings less than 1000 feet and/or visibility less than 3 miles affecting over 50% of the area at one time, or extensive mountain obscuration

AIRMET TANGO (Turbulence)
Moderate turbulence, or sustained surface winds of 30 knots or more

AIRMET ZULU (Icing)
Moderate icing, or freezing levels

Question 6

SIGMET Issuance Criteria

Answer 6

Severe or greater turbulence over a 3,000-square-mile area
Severe or greater icing over a 3,000-square-mile
IMC conditions over a 3,000-square-mile area due to dust, sand, or volcanic ash.

Question 7

Convective SIGMET Issuance Criteria

Answer 7

An area of thunderstorms affecting 3,000 square miles or greater, with thunderstorms affecting at least 40% of the area
A line of thunderstorms at least 60NM long, with thunderstorms affected at least 40% of the length
Severe or embedded thunderstorms affecting any area that are expected to last 30 minutes or more

Severe surface weather including:
surface winds greater than or equal to 50 knots
hail at the surface greater than or equal to 3/4 inches in diameter
tornadoes

Question 8

SIGMET Valid Times

Answer 8

4 hours, 6 hours for hurricanes