Middle Latitude
Cyclones
By Jenny Barnes
An Introduction:
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Mid-Latitude cyclones are also known as
extra-tropical or frontal cyclones
These weather systems are named for
occurring in the middle latitudes of earth.
They are classified as large, traveling,
cyclonic storms up to 2000 kilometers in
diameter with centers of low atmospheric
pressure.
Cause the extreme weather conditions in
the middle latitudes, including ours.
The Development of a Mid-Latitude
Cyclone:
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Mid-Latitude cyclones are the result of interacting of
the warm tropic and cold polar air at the polar front.
In their mature stage, mid-latitude cyclones have a
warm front on the east side of the storm's center
and a cold front to the west. The cold front travels
faster than the warm front. Near the end of the
storm's life the cold front catches up to the warm
front causing a condition known as occlusion.
The polar front theory of a developing wave cyclone
(previous known as the Norwegian cyclone model)
shows this progression from birth to decay:
A: show the development of the wave.
B: the cyclonic circulation and the establishment of a low pressure area
C: the cold front overtakes the warm front and an occlusion-front is
formed
D: the development of the occlusion continues and the cyclone has
reached its mature stage.
Direction of Mid-Latitude Cyclone
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The wind travels from High to Low
pressure. Mid-Latitude has a very
low pressure, therefore what
direction would the wind be traveling
in a mid-latitude cyclone found over
the US ??
Like always, wind will travel
around a low pressure area
(in the Northern Hemisphere)
counterclockwise and
inward!!!!!!
(This is important, remember it)
Effects of Mid-Latitude Cyclones
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Normally, exist for about 3 to 10 days
moving in a generally west to east
direction. They are rarely motionless and
travel around 1200 kilometers a day
directed by the polar jet stream. (1)
Various types of precipitation can occur
including rain, freezing rain, hail and
snow.
latitude cyclones cause far less damage
than tropical cyclones or hurricanes.
Although rare, mid-latitude cyclones can
have winds as strong as what is
associated with a weak hurricane.
Examples of past Mid-Lat cyclones:
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March 1993: East coast had reported winds of up
to 90 knots had over 50 billion tons of snow.
Ice Storm in Oregon, 1998 and 2004
The affect of Climate Change/
Global Warming
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As sea/land temperatures are increasing,
the difference between the tropic warm air
meeting the cold polar air would decrease
therefore possibly weakening mid-latitude
cyclones or causing them to occur less.
However, with sea surface temperatures
increasing, this would cause hurricanes,
tropical cyclones, or tropical storms to
happen more frequently or more intensely
due to their energy arriving from the
warm waters.
Sources Used:
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PhysicalGeography.net, Fundamentals of
Physical Geography <
http://www.physicalgeography.net/funda
mentals/7s.html>.
Wikipedia: <
http://en.wikipedia.org/wiki/Extratropical_
cyclone>.
Realclimate:
<http://www.realclimate.org/index.php?p
=181>.