stability of air Flashcards
what determines the pattern of weather and the type of cloud that will form?
the way in which temperature varies in conjunction with atmospheric humidity.
what happens in an adiabatic process?
in an adiabatic process, heat is neither lost nor gained by a gas
what is it called when in rising air currents, pressure and temperature decrease?
adiabatic lapse rate
what is environmental lapse rate?
the rate of temperature decrease with a gain in altitude.
Environmental lapse rate is a recording of what?
it is a recording of the atmosphere’s actual temperature with a gain in altitude
what is the average temperature lapse rate? (up to 35,000ft)
2 degrees per thousand feet.
what is dry adiabatic lapse rate (DALR)? And what is the rate?
The DALR is the rate at which the temperature of unsaturated air changes as a parcel ascends or descends through the atmosphere. The DALR is approximately 3°C/1000 feet.
how will saturation occur in a rising parcel of air that is DALR?
if the ascent is sufficiently high, when the parcel
of air’s temperature reaches the dew point temperature saturation will occur in the rising parcel of air. above this height, the now saturated air will cool as it rises.
what is saturated adiabatic lapse rate?
The rate at which saturated air cools when it ascends (when considering) the effect of latent
heat release.
what is the SALR rate?
1.5C per 1000ft
is SALR a fixed rate like DALR?
no, it depends on the amount of water vapour available for condensation.
what is required for SALR?
latent heat is required for the process, the heat is taken from the air parcel in which the droplets are evaporating, thus
counteracting the heating due to comp
what is stability?
stability refers to the the tendency of an object to return to its original position after a disturbance.
define stable
if a parcel returns to its original position after a disturbance
define unstable
if a parcel doesn’t return to its original position after a disturbance
define neutrally stable
If the parcel of air is forced to move either up
or down and then remains in the moved
position, after the disturbance has ceased, it
is said to be neutrally stable
the 3 types of stability are determined by?
temperature, humidity and environmental lapse rate
What are the conditions of stable air?
denisty of air is greater then surroundings, air tends to resist vertical movement and air is stable if ELR is less than SALR. and DALR is stable if the observed lapse is less than SALR
what are the conditions of unstable air?
Dry air is unstable, if the environmental lapse rate is
greater than the Dry Adiabatic Lapse Rate (DALR). And saturated air is unstable, if the environmental lapse rate is greater than the saturated adiabatic lapse rate.
what are the coniditions of conditional instability?
Conditional instability occurs when the Environmental Lapse Rate is between both the dry and saturated lapse rate. The air will become unstable if the air becomes saturated.