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Hour.3
By: Sam Hurwitz, Alex Payne, and Joey Peirick
Global Winds
Global winds are winds that blow steadily
from specific directions over long
distances.
Like local winds, global winds are created by
the unequal heating of Earth’s surface. But
unlike local winds, global winds occur over
a large area.
Global Convention Currents
• Warm air rises at the equator and the cold air
•
•
sinks at the poles
Global winds develop by temperature difference
between the equator and the poles that produce
giant convention currents in the atmosphere.
This difference in pressure causes winds at
Earth’s surface to blow from the poles toward
the equator.
The Coriolis Effect
• The way Earth’s
•
rotation makes wind
curve is called the
Coriolis effect.
Because of the
Coriolis effect, global
winds in the Northern
Hemisphere gradually
turn toward the right.
Global Winds Belts
• The major global wind belts are the trade
winds, the polar easterlies, and the
prevailing westerlies.
• The calm air include the doldrums and the
horse latitudes.
Doldrums
• Near the equator, the sun heats the
surface strongly.
• Cool air moves into the area, but is
warmed rapidly and rises before it moves
very far.
• Regions near the equator with little or no
winds are called Doldrums.
Horse Latitudes
• Latitude is the distance from the equator,
measured in degrees.
• Called Horse Latitudes because sailors
would run out of water and food for the
horses and had to throw them over board.
Trade Winds
• When the cold air over the horse latitudes
sink, it produces a region of high pressure.
• The high pressure causes surface winds to
blow towards the equator.
• It is called trade winds because sailors
would use these to move ships carrying
goods to different countries.
Prevailing Westerlies
• In the mid-latitudes between 30 and 60
degrees North and South, winds blow
towards the poles turned east by the
Coriolis effect.
Polar Easterlies
• Cold air near the poles sinks and flows
back toward lower latitudes.
• The mixing of warm and cold air along the
polar front has a major effect on weather
in the U.S
Jet Streams
• Jet streams are bands of high speed winds
about 10 km. above the surface.
• These winds are 100’s of km. wide, but
only a few km. deep.
• Jet streams usually flow from the west to
the east at speeds of 200 to 400 kph.