WIND

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WIND

• class, I dont think were in Kansas anymore

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WIND!

• Why is it important?
• What causes the wind to blow?

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Why is the wind important?
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Todays Wind

• Boston Current Conditions
• 41F at Logan Airportas of 455 PM Partly Cloudy
• 32 F RealFeel temp
• 11 mp/h Wind speed
• SSW Wind direction
• 64 Relative humidity
• 30.43 in Barometric pressure
• 10 miles Visibility
• 1 of 10 Tanning index

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What causes the wind?

• A) The rotation of the Earth
• B) Solar flares (solar winds)
• C) God shaking the world (like a snow globe)
• D) Scientists dont know
• E) Differences in atmospheric pressure

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What Causes the Wind?

• Differences in atmospheric pressure cause the
  wind to blow
• Wind moves from areas of high pressure to areas
  of lower pressure (you can prove it blow onto
  your palm. The higher pressure air moves toward
  the lower pressure air)
• HIGH LOW

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What causes the differences in air pressure?

• (hint it has to do with what weve learned so
  far)

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What causes the differences in air pressure?

• 3 facts to review
• air pressure is the weight of a column of air
  above a unit area (1 squared meter)
• The denser the air, the higher the pressure
• Cold air is denser than warm air

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What causes differences in air pressure?

• Differences in the heating of Earths atmosphere
  causes differences in air pressure
• Some parts of the Earth receive direct rays from
  the sun all year and are always warm. Other
  places receive indirect rays, so the climate is
  colder.

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Wind is caused the by convection of air

• Warm air, which weighs less than cold air, rises.
  Then cool air moves in and replaces the rising
  warm air. This movement of air is what makes the
  wind blow.

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2 Classes of Winds
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1. Local Winds

• Caused by differences in heating of the Earths
  surface within a small area

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Local Winds - convection
Suns Radiation
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High Density
Hot Air Molecules Rise and cool
Low Density
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Local winds
For example, clouds can cause a difference in air
temperature and air pressure, creating a wind
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Sea Breeze
Ever notice that its breezy by the water?
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Sea Breeze
The suns radiation heats land faster than water.
The air above land is warmed by conduction while
the air above water stays cool. The difference
in temperature and pressure causes cool sea
breezes to blow toward land
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Land Breeze
At night, land cools faster than water. The warm
water heats the air above it by conduction. The
difference in temperature and pressure cause cool
winds to blow toward the water
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Monsoons sea and land breezes that last a long,
long time
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Katabatic wind Mountain Breezes
As mountain tops/slopes receive first sunlight,
they warm. The cool valley air flows up the slope
to take its place. Cool winds can push water
vapor up, forming clouds and rain or snow, like
it does West of the Rocky Mountains
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Anabatic Winds Valley Breezes

• By midday, the valley becomes warmed and the
  slopes cool. Cool mountain air flows down to the
  valley.
• The dry winds can warm up a winter day by 50C or
  o105 F, but can also be faster than hurricane
  winds!

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Examples include chinooks in Western Canada,
Santa Ana in California and Mistral in France
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Global Winds

• Produced by the movement of air between the
  equator and the poles long distances!

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Global Winds calm spots

• Polar Easterlies
• Prevailing Westerlies above 60 degrees
• Horse Latitudes (neigh) calm at 30
• Trade Winds Easterlies
• Doldrums calm at the equator

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Global Winds
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Westerlies come from the West

• They do not GO west, they COME FROM the west.
  Got it?
• Easterlies...
• Northwesterlies
• Southeasterlies well you get the idea.

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But a West wind goes West

• DOH

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Coriolis Effect

• If the globe did not rotate, cold air from the
  poles should travel a straight line to the
  equator, but because the Earth rotates, global
  winds curve rather than fall straight

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Coriolis Effect
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Earth spins East
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Drag makes polar winds bend West, equatorial
winds go East
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More West, More East
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And so on
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How is Wind Measured?

• With ANENOMETERS!

Aerovane, Lazer doppler anenometer and anenometer
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Wind Chill a measure of heat loss from your body
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And Finally, Jet Streams

• About 10km (6 mi) above the Earths surface,
  where heat dissipates
• 100s of miles wide, only a few mi deep
• Blow from west to east in a wave
• Travel 125-250 mph (a 747 travels at around
  580mph)
• Planes often borrow these to save fuel and time

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The Power of the Wind

• The sun radiates 174,423,000,000,000 kilowatt
  hours of energy to the earth per hour. ( the
  earth receives 1.74 x 10 17 watts of power )
• About 1 to 2 of the energy from the sun is
  converted into wind energy... That is about 50 to
  100 times more than the energy used by all plants
  on earth to grow!

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Wind Powering the Future?
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Summary

• Winds are caused by unequal heating of the
  Earths surface
• Its measured using anenometers
• 2 types of wind local, global
• Coriolis Effect is due to the Earths rotation

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Coming Up Next

• Wild Winds Tornados, Hurricanes
• Wow, Water! Cloud Formation and Precipitation