Chapter 8 - Adiabatic Processes And Stability Flashcards
What is an adiabatic process?
When there is a change in temperature without a heat transfer
What is the environmental lapse rate (ELR)?
The temperature lapse rate measured on the day.
What is the dry air lapse rate (DALR)?
3degC/1000ft and is based on empirical data so is constant.
What is saturated air lapse rate (SALR)?
1.8degC/1000ft and is based on empirical data so is constant. except its not due to condensation occurring.
When does adiabatic cooling for an air mass stop?
When condensation starts due to latent heat being transferred.
What can be said about the atmosphere when the ELR is larger than DALR?
It is unstable.
What can be said about the atmosphere when the ELR is smaller than SALR?
It is stable.
What can be said about the atmosphere when the ELR is smaller than DALR and larger than SALR?
it is conditionally stable.
What can be said about the atmosphere when the ELR is the same as DALR or SALR?
it is neutrally stable.
What conditions can be expected in stable air?
Smooth flight
Often poor visibility
Frost or dew
Surface temperature inversion overnight.
Layered stratus type clouds
Continuous or intermitent precipitation
light to moderate rime icing in cloud
freezing rain.
What conditions can be expected in unstable air?
Moderate to severe turbulence
Gusty winds
Heaped clouds (cumulous)
Showers
Good visibility out of showers
Moderate to severe clear icing in clouds
Thunderstorms
Hail
Tornados
What effect will condensation have on an unstable parcel of air?
it will increase its instability due to latent heat being released into the air thus warming it further making it even less dense.
What is the lowest temperature at which liquid water can exist?
-40degC.
What is orographic lifting?
When wind pushes air upwards due to an obstical such as a moutain side.
What is frontal lifting?
When the warmer air from a warm front lift over the colder air from the cold front.
