Weather
Cloud Formation
May 19, 2008
Adiabatic Temperature Changes
• When air is allowed to expand, it cools,
and when its is compressed, it warms.
• Do you know of any examples?
Water’s Changes of State
Adiabatic Rate
• Dry adiabatic rate – only applies to air that
is unsaturated
– 10°C for every 1000 meters
• Wet adiabatic rate – only applies to air that
is saturated
– 5-9°C for every 1000 meters
• Why do you think there is a difference
between the wet and dry adiabatic rate?
• The latent heat absorbed or released by
the water.
Processes That Lift Air
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Orographic Lifting
Frontal Wedging
Convergence
Localized Convective Lifting
Orographic Lifting
• Orographic lifting is the lifting that occurs
when elevated terrains, such as mountains,
act as barriers to air flow.
Frontal Wedging
• Frontal wedging is what happens when a
mass of warm air and a mass of cool air
come together. The less dense warm air
rises above the more dense cool air.
Convergence
• Convergence is what happens when there
is a collision between contrasting air
masses.
Localized Convective Lifting
• Localized convective lifting is caused by
unequal heating of the Earth’s surface.
This causes pockets of air to be warmed
more than the surrounding air.
Summary
• What is adiabatic temperature change?
• Why is there a difference between the dry
adiabatic rate and the wet adiabatic rate?
• Describe orographic lifting.
• Describe frontal lifting.
• Describe convergence.
• Describe localized convective lifting.