Stability And Cloud Formation Flashcards
Whats the verticle movement of air called?
Convection.
Whats the horizontal movement of air called?
Advection.
What altitude is the friction layer?
3000ft
What is orographic lift?
Air moving up a mountain.
When air passes over a mountain, if the altitude of the air sinks back, what is the atmospheric stability?
Stable.
When air passes over a mountain, if the altitude of the air stays flat, what is the atmospheric stability?
Neutral
When air passes over a mountain, if the altitude of the air continues to rise, what is the atmospheric stability?
Unstable.
Whats used to measure the lapse rate?
Radiosonde.
What is adiabatic cooling?
Air rising and then expanding.
What is adiabatic warming?
Air sinks and compresses.
Provided water vapour does not condense when it rises, the parcel of air cools at x degrees / 1000ft.
3
Provided water vapour does not condense when it rises, the parcel of air cools at x degrees / 100m.
1
What is the dry adiabatic lapse rate in feet and metres?
3’/1000ft - 1’/100
What is the saturated adiabatic lapse rate for 1000ft?
1.8’
What is the saturated adiabatic lapse rate for 100m.
0.6.
Why does a saturated adiabatic lapse rate vary with height?
Latent heat released due to change of state.
Whats is the environmental lapse rate per 1000ft?
1 degree
Absolutely stable atmosphere - air (does/does not) rise buoyantly?
Does not.
In a blank blank atmosphere, air rises buoyantly.
Absolutely unstable.
What happens to air in an absolutely unstable air?
It rises and forms a cloud.
Any thing below the dew point is deemed at what lapse rate?
Dry.
What stability is turbulence is likely?
Absolute instability.
What cloud types would you see in absolute instability?
Cumulus, towering cumulus, cumulonimbus,
What is conditional instability?
ELR is in between DALR and SALR
In a conditionally unstable atmosphere, blank air does not rise buoyantly.
Unsaturated.
In a conditionally unstable atmosphere, blank air does rise buoyantly.
Saturated.
If air is cooled from below, what is the stability?
Stable.
If air is warmed from below, what happens to the stability?
Unstable.
How do you get rid of cloud?
Adiabatic warming (subsidence) -solar radiation
ELR less than 1.8°C/1000ft air will be
absolutely blank, dry or saturated.
Stable.
ELR more than 3°C/1000ft air will be
absolutely blank, dry or saturated
Unstable.
ELR between 3°C/1000ft and
1.8°C/1000ft, air will be blank blank.
–Unstable if saturated
–Stable if dry
Conditional instability.
What are the standards for a DALR?
Fluffy cloud - fat water droplets - flat line on altitude tempurature graph
What are the standards for SALR?
Stable - smooth - stratus - small water droplets - steep line on a alt temp graph
When two humid, but yet unsaturated air masses with different temperatures mix, the result can be…
Cloud formation.
In winter, after breaking through a low level inversion during descent and assuming the pilot does not intervene, what will happen to visibility?
Decrease.
In winter, after breaking through a low level inversion during descent and assuming the pilot does not intervene, what will happen to thrust?
Increase.
A surface based inversion is a characteristic of nocternal blank on blank nights
Radiation clear
Lower layers of air are heated by x, which means transferring heat by molecular interactions between ground and air.
Conduction
How could a flight crew visually identify that a tropical squall line is about to pass over their destination aerodrome, and what hazard should they expect to encounter on the approach?
Roll cloud
What are the primary factors driving heat transfer from the ground to the lower levels of the atmosphere?
Conduction and turbulence
A moist, stable layer of air is forced to rise against a mountain range and the stability does not change. Which of the following phenomena may develop?
Stratiform clouds.
