Ch 3 - Weather

Question 1

atmospheric stability

Answer 1

the resistance of the atmosphere to vertical motion

Question 2

Front characteristics

Answer 2

change in temperature
continuous decrease in pressure followed by an increase as the front passes
shift in wind direction

Question 3

Unstable air

Answer 3

cumuloform clouds
showery precipitation
rough air (turbulence)
good visibility

Question 4

Stable air

Answer 4

stratiform clouds/fog
continuous precipitation
smooth air
fair to poor visibility in haze and smoke

Question 5

Lapse rate

Answer 5

the rate at which temperature falls with an increase in altitude

Question 6

Three conditions required to produce thunderstorms

Answer 6

sufficient water vapor
unstable lapse rate
initial lifting force (upward boost)

Question 7

wind shear turbulence

Answer 7

a hazardous and invisible atmospheric phenomena that can occur within 20 NM of a thunderstorm

Question 8

microbursts

Answer 8

small-scale intense downdrafts which, as they get near the ground, spread outward from the center in all directions

Question 9

squall line

Answer 9

nonfrontal, narrow band of active thunderstorms that often develop ahead of a cold front

Question 10

Effects of structural icing

Answer 10

decrease in lift
weight and stalling speed increase for fixed wing, propellers may stall on rotary wing
decrease in thrust
increase in drag

Question 11

structural icing

Answer 11

occurs on an aircraft whenever supercooled condensed droplets of water make contact with any part of the aircraft that is also at a temperature below freezing

Question 12

Radiation fog

Answer 12

(ground fog) formed when terrestrial radiation cools the ground, which in turn cools the air in contact with it. When the air is cooled to its dew point (or within a few degrees), fog will form. This fog will form most readily in warm, moist air over low, flatland areas on clear, calm (no wind) nights.

Question 13

Advection fog

Answer 13

(sea fog) formed when warm, moist air moves (wind required) over colder ground or water (i.e., when an air mass moves inland from the coast in winter)

Question 14

Upslope fog

Answer 14

formed when moist, stable air is cooled to its dew point as it moves up along a sloping terrain (wind required). Cooling will be at the dry adiabatic lapse rate of approximately 3 degrees C per 1000 ft.

Question 15

Precipitation-induced (rain or drizzle) fog

Answer 15

most commonly associated with frontal activity and is formed by relatively warm drizzle or rain falling through cooler air. Evaporation from the precipitation saturates the cool air and fog forms. This fog is especially critical because it occurs in the proximity of precipitation and other possible hazards such as icing, turbulence, and thunderstorms.

Question 16

Steam fog

Answer 16

forms in the winter when cold, dry air passes from land areas over comparatively warm ocean waters. Low-level turbulence can occur and icing can become hazardous in steam fog.

Question 17

Flight performance decreases:

Answer 17

As:
atmospheric pressure decreases
altitude increases
temperature increases
humidity increases

Question 18

METAR

Answer 18

Aviation routine weather reports- observation of current surface weather reported in a standard international format

Question 19

TAF

Answer 19

Terminal aerodrome forecasts - established for 5 SM within an airport

Question 20

ASOS

Answer 20

Automated surface observing system - primary surface weather observing system of the US

Question 21

AWOS

Answer 21

Automated weather observing system - derived from an automated system

Question 22

WST

Answer 22

Convective SIGMET (significant meteorological information) - issued for severe thunderstorms with surface winds greater than 50 knots, hail > 3/4” in diameter, or tornadoes.