Chapter22 questions and answers certified 2025

Chapter 2: Stability and Lapse Rates
Question and answers rated A+
To find the height of a cloud base when you know the temperature and the
dew point: - correct answer ✔(TEMP-DEWPOINT) X 400 = _____ft AGL


i.e Ts=20
Td=5
Dewpoint lapse rate = 2.5/1000'


(20-5)=15/2.5=6 x 1000 = 6000' AGL


Finding height of the freezing level - correct answer ✔-Need base of cloud
and dewpoint
-Difference of base temperature to 0
-Difference/SALR (1.5) x 1000


-i.e Base=6000'
Td=5


>5-0=5
>5/1.5 = 3.4 x 1000 = 3400
>Freezing level = 6000+3400 = 9400' AGL


Laser Ceilometer - correct answer ✔-device used to accurately measure the
base of clouds
-20' is the round off point to the nearest 100'

, Adiabatic Expansion & Compression - correct answer ✔-Rising air expands
and cools
-Sinking air compresses and heats up


Lapse Rate - correct answer ✔The rate of change of temperature with
altitude


TALR - correct answer ✔Lapse rate including dew point
i.e DALR - DPLR
=3.0/1000'-0.5/1000'
TALR = 2.5/1000'


Standard lapse rate - correct answer ✔2.0°C per 1000'
-Used in calibration of altimeters
-ICAO-1.98


Dry Adiabatic Lapse Rate (DALR) - correct answer ✔Unsaturated air will
cool at a rate of 3°C per 1000'
-(no moisture, no pressure change with height)


Saturated Adiabatic Lapse Rate (SALR) - correct answer ✔1.5°C per 1000'
-Occurs when during condensation in a cloud, latent heat is released,
decreasing the rate of cooling.


Environmental Lapse Rate (ELR) - correct answer ✔-the "now" lapse rate
Stability or instability based on the relationship between the temp. of the rising
parcel of air and the temp. of the surrounding air.