Download Winds - SD67

Winds
“Always blow from High to Low”
“Ferrel’s Law” and the
“Coriolis Force / Effect”
• Is a deflective force caused by the rotation
of the earth on its axis
• All particles in motion are deflected toward
the right in the Northern Hemisphere
• All particles in motion are deflected toward
the left in the Southern Hemisphere
That explains it 
In Canada, water flushes
clockwise!
In Australia, water flushes
counter - clockwise!
Coriollis Effect:
Tendency for winds to deflect
to the RIGHT in the NORTH
and to the
LEFT in the SOUTH
Really Nice but
you are Lazy Students
you are
Winds
• Are named for the direction from which
they blow, not the direction they are going
North
West
Wind
“Hadley Cell”
• On or near the equator, where solar radiation is
greatest, air is warmed at the surface and rises
• This creates a band of low air pressure, called
the intertropical convergence zone (ITCZ)
• On or near the equator, where solar radiation is
greatest (between 12oN and 8oS), air is warmed
at the surface and rises
• The ITCZ draws in surface air from the
subtropics
• This subtropical air rises into the upper
atmosphere, then begins flowing horizontally to
the North and South Poles
Warm, moist air
Cool, dry air
• The Hadley cell eventually returns air to the
Earth’s surface near 30o North and South
“Down in the Doldrums”
• This is the calm, windless area around the
equator
• Sailors would get caught in them, going
nowhere…
Trade Winds or Tropical Easterlies
• These winds are deflected from east to
west as they travel toward the equator by
the coriolis force
Northeast
trades
southeast
trades
Trade Winds
• Discovered by Christopher Columbus
• Smart sailors sought out the trades to go
west (sailed fast)
• The other portion of that surface air moves
towards the poles from the subtropical
high zone
• This air, also deflected by the Coriolis
Force, are called the Westerlies
Prevailing southwesterlies
Prevailing northwesterlies
The Westerlies
• These powered Columbus’ return trip to Europe
• They are also responsible for the better surfing
found on the Pacific side of North America (blow
in the same direction as the waves heading
toward shore, building up their height)
Horse Latitudes
• This is another calm area found between the
trade winds and the westerlies
• Caught in this calm for weeks, sailors could
starve
• Horses, common cargo
back then, would be
thrown overboard to
lighten the load 
Polar Easterlies
• The high pressure of the “Polar High”
forces air away towards the “Polar Low”
Polar northeasterlies
Polar southeasterlies
Remember, air flows from highs to
lows

HIGH
LOW
HIGH
LOW
HIGH
LOW
HIGH
WHAT IT
REALLY
LOOKS
LIKE:
DRAW IT!
LAND AND SEA BREEZES:
• During the day, the land heats up more
rapidly than does the sea. Air rises over
the land, creating a low-pressure area.
Cooler air flows in to this area from the
sea, creating a sea breeze.
• During the night, the land cools more
rapidly than the sea, and the reverse
flow, a land breeze, occurs.
Sea Breeze
Land Breeze
Valley and Mountain Breezes:
• Mountain Breeze: Katabatic Wind
Cool Air shoots down the sides of mountain
down into the valley. In the summertime, this
occurs at night.
• Valley Breeze:
Anabatic Wind.
Warm air rises up
the mountain
sides, causing
breeze which
flows up the
valley. During
the summer, this
occurs during the
day.