J. Shevlin April 11, 2012 Eastern Illinois University

 What is wind?  What causes wind to form?

At the end of class, you will be able to: Relate air pressure and wind direction Explain why winds flow in a curved direction Discern global winds from local winds Describe the three main global wind patterns on Earth Explain two types of local wind patterns

 Wind  Coriolis effect  Jet stream  Trade winds  Westerlies  Polar easterlies

 Wind is air in motion. Formed by differences in pressure  Caused by uneven heating of the atmosphere  Law of diffusion: moves from high to low  Greater pressure difference = faster winds

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 Why doesn’t wind blow directly from the poles to the equator?

 Thought to consider: is the Earth in a fixed position?

 Wind movement affected by Earth’s rotation Results in a curved path of motion Depends on hemisphere you are in  Northern hemisphere- winds curve to the right  Southern hemisphere- winds curve to the left

 The Coriolis effect is the curving motion of objects caused by the Earth’s rotation

 Global winds Pattern of circulation across the Earth Travel great distances Travel in a specific direction  Local winds Travel short distances Can blow from any direction

 Trade Winds  Westerlies  Polar Easterlies  Doldrums  Horse Lattitudes

 What do you think may cause global wind patterns?

 Thoughts to consider:  Are regions of high pressure only ever near the poles?  Are regions of low pressure only ever near the equator?

 High pressure belts near 30 o N, 30 o S  Low pressure belts near 60 o N, 60 o S  Result in patterns of rising and sinking air Sounds familiar…Convection?

 Jet stream- narrow belt of high speed winds Found in upper troposhere, lower stratosphere Do not follow regular patterns  Change positions frequently Affect weather movement

 Local winds are affected by an area’s geography Results in wind blowing from any direction Examples:  Sea breeze  Land breeze

 Why does breeze travel one way in the daytime and in the other direction during the nighttime?  Thoughts to consider:  is ground a good conductor of heat?  Is water a good conductor of heat?