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Cold Advection
cold air moves into a warmer region
Cold advection is the process in which the wind blows from a region of cold
air to a region of warmer air.
The following animation depicts a very simple example of cold advection.
The horizontal lines are isotherms in degrees Fahrenheit
and the arrows represent wind vectors.
Winds are blowing from a region of cold air to a region of warmer air, which
results in cooling of the warmer region.
As the cold advection persists, temperatures
in the warmer region will begin to decrease as the colder air moves into
the region of warmer air.
Animation by:
Van Dorn
The net result of cold advection is to make a
region cooler.
The animation below shows (in a very general sense) how cold
advection can lead to sinking motion.
Cold advection is occurring in Figure A while
Figure B shows a vertical cross section through the region of
cold advection.
In Figure B, the horizontal lines are
isobars
and the arrows represent
wind vectors. It is important to
note that Figure A is along the ground and that Figure B is from the ground
up to a higher level in the atmosphere, directly above the region of
cold advection.
Animation by:
Van Dorn
With the onset of cold advection (Figure A),
the isobar in
Figure B starts to bend downward since
colder air is more dense and occupies less room
than warmer air.
The bending of the isobar
due to cold advection creates a localized area of
low pressure
("L" in Figure B"), thus altering the
pressure
gradient force. As air moves from the regions of
high pressure
("H" in Figure B) to the local region of
lower pressure, air is pushed downward
from above, which is the sinking motion that is caused by cold advection.
advection
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warm advection
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