Atmospheric Stability Flashcards
As the temperature of the air increases, it’s density decreases and, if it is surrounded by colder dense air, it will rise.
True or False?
True.
The temperature of air rises when it is squeezed or compressed. True or False?
True.
What is Adiabatic cooling?
The temperature of Air rises when it is squeezed or compressed.
The temperature of Air decreases as it expands.
True or False?
True.
During such changes in temperature, no heat is transferred from one part of the atmosphere to another because the air is a poor conductor.
True or False?
True.
We may consider the the air that is undergoing the Adiabatic temperature change to be a parcel acting independently from the surrounding atmosphere.
True.
What is Lapse rate?
A change of temperature with height
What is Dry Adiabatic Lapse Rate (DALR)?
The change of temperature with height due solely to Adiabatic expansion or compression of a parcel of unsaturated (Dry) air.
What is the DALR?
3 degrees per 1,000ft
What is Saturated Adiabatic Lapse Rate (SALR)?
When water vapour in the atmosphere condense, a change of state occurs and laten heat is released.
What is the SALR
1.5 degrees per 1,000ft
It is important to remember that amount of water vapour required to cause saturation and condensation decreases as the temperature is lowered.
True
What is Environment Adiabatic Lapse Rate (ELR)?
The change of temperature with height that actually exists at a particular time within the atmosphere
What is the ISA Lapse Rate?
1.98 degrees per 1,000ft
Air is said to be_________ if it rises.
Unstable
When is Air said to be stable?
If the air is not rising
Absolute stability is when the ______ is less than both the _______ and _______
ELR
SALR and DALR
When does conditional stability exist?
When the ELR lies between the DALR and SALR.
What is absolute instability?
When the ELR is greater than the SALR and DALR
What other factors can cause the air to rise?
F rontal
O rographic
C onvergence (depression/thermal)
T urbulence
What is a front?
The boundary between two large areas of air which are different temperatures.
What is frontal lifting?
When cold air replaces warm air by undercutting it (because cold air is denser), forcing the warm air to rise.
What is orographic lifting?
Prominent geographical features (Mountains) cause Air to rise as it attempts to pass over the mountains.
Stable air effected by orographic lifting will…
Descend Lee side
Unstable air affected by orographic lifting will.
Continue to rise
Convergence depression causes what type of movement in the atmosphere?
Vertical
Where relatively low pressure exists at the surface of a depression Air will tend to move in from all directions to equalise the pressure. The accumulation of air is called a convergence
True.
A surface is heated, as it warms the air in contact with it. Hearing of different surfaces causes unequal temperature rise, producing a local convection current. As Air rises the pressure drops at the ground and air converges to equalise.
True
What is thermal turbulence?
Turbulence produced by unequal surface heating.
What is Mechanical turbulence?
a result of friction between the air and rough surface.
The intensity of mechanical turbulence depends in which 3 factors?
1) Strength of surface wind
2) Stability or Air
3) nature of the ground
