cloud development and precipitation - I Flashcards
What is stability in the atmosphere?
the ability for the air to return to its origin after displacement
What is a stable atmosphere?
returns to original position after displacement
What is a neutral atmosphere?
remains in new position after being displaced
What is an unstable atmosphere?
accelerates from its original position
What is forced motion?
the push of air upwards
What is buoyant motion?
air rising because it is less dense than its surroundings
What is positive buoyancy?
when the temperature of the air parcel > temperature of the environment, density of the air parcel < density of the environment
What is negative buoyancy?
when the temperature of the air parcel < temperature of the environment, density of the air parcel > density of the environment
How do you solve for environment density?
pressure/(gas constant)(environment temperature)
How do you solve for dry air parcel density?
pressure/(gas constant)(parcel temperature)
When the temperature of an air parcel > temperature of the surrounding environment, the atmosphere is …
unstable (linked with positive buoyancy)
When the temperature of an air parcel < temperature of the surrounding environment, the atmosphere is …
stable (linked with negative buoyancy)
When the temperature of an air parcel = temperature of the surrounding environment, the atmosphere is …
neutral
What is lapse rate?
the rate of temperature decrease with height (- temperature difference/height difference)
What is environmental lapse rate?
the rate at which the surrounding air temperature decreases with altitude
What is parcel lapse rate?
an air parcel’s change in temperature when it is displaced vertically
What is the adiabatic process?
when an air parcel does not have any heat exchange with the environment when it is vertically displaced
What is dry adiabatic lapse rate?
the rate of temperature decrease of a rising unsaturated air parcel (10°C/km)
Do rising saturated air parcels cool less or more than rising unsaturated air parcels?
cool less
What is moist adiabatic lapse rate?
the cooling rate for moist air parcels (4°C/km near ground, 6-7°C/km lower-mid troposphere)
What condition creates an absolutely stable atmosphere?
environment lapse rate > moist adiabatic lapse rate
What condition creates a conditionally unstable atmosphere?
dry adiabatic lapse rate < environment lapse rate < moist adiabatic lapse rate
What condition creates an absolutely unstable atmosphere?
environment lapse rate < dry adiabatic lapse rate
How are active clouds formed?
formed in unstable air, warm air with positive buoyancy is pushed upwards
How are passive clouds formed?
formed in stable air, through lifting and radiative cooling
