Download Intertropical Convergence Zones

Intertropical Convergence Zones
• Just like there is a true north pole and
magnetic north pole, there is more than
one equator.
• The geographic equator is at 0° latitude.
• The meteorological (Intertropical
Convergence Zone) shifts north and south
of the geographical equator.
• The ITCZ is where the trade winds meet.
Intertropical Convergence Zone
• The ITCZ is a wavy imaginary line marking the
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temperature equilibrium between the northern
and southern hemispheres.
It is not a straight line because there is more
land mass in the northern hemisphere than in
the southern hemisphere.
The ITCZ (meteorological) equator shifts north
and south of the geographical equator with the
seasons.
Intertropical Convergence Zone
• The ITCZ equator
marks where the
atmospheric
circulation is the same
on both sides.
How Does Air Circulation Make Deserts?
• At about 30° north and south latitude, the
Hadley and Ferrel cells meet.
• The juncture of these cells is where dry air
sinks.
• Dry air doesn’t bring rain to the area, yet
there is still lots of evaporation – thus
forming deserts.
How Does Air Circulation Cause Deserts?
• Since more evaporation also occurs in the
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oceans at these latitudes, and there is a lots of
evaporation, the ocean water in this area is
saltier.
This area is called the Horse Latitudes because
the winds would die down and strand sailors,
similar to the doldrums. The stranded ships ran
low on fresh water, so sailors drank the water
and discarded the carcasses of dead horses
overboard.
Monsoons and Cyclones
• Monsoons are seasonal wind patterns resulting
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in summers with lots of rain and dry winters.
Warm, moist air from the oceans replaces hot
air from the land bringing rain during the
summer.
In winter the cycle is reversed, with the colder
land air flowing toward the ocean, leaving the
area dry.
Monsoons and Cyclones
• http://online.wsj.com/video/typhoon-
slams-philippines/6E6E9C26-EB99-4F4680EE-98CC84745F12.html
• Pictures
Monsoons and Cyclones
• Cyclones are large rotating storms of low-
pressure air spiraling into the center.
• Cyclones are called typhoons in the Pacific
Ocean and hurricanes in the Atlantic
Ocean.
• The winds of cyclones spiral in toward the
center due to the Coriolis Effect.
Monsoons and Cyclones
• Cyclones form when convection currents cause
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warm moist air to be drawn into a low pressure
area.
The rising moist air forms rain pulling more air
into the system.
When a cyclone moves inland, the air is not a
hot or moist, so no new air is sucked into the
system and the cyclone loses strength.
Monsoons and Cyclones
• Extratropical cyclones, those occurring
outside the tropics, are not called
hurricanes.
• These storms occur where the polar winds
and westerlies meet forming nor’ easters
as in the “perfect storm”.
Monsoons and Cyclones
• What is the value of cyclones?
• Tropical cyclones take heat from the tropics and
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release it into the atmosphere.
A tropical cyclone can release as much energy in
one day as the US uses in a year.
Extratropical cyclones mix warmth from the
tropics with cold polar air redistributing heat.
THE END, END, END.