Atmospheric Pressure and Winds

Atmospheric Pressure and WindsJ. ShevlinApril 11, 2012Eastern Illinois UniversityAs Class BeginsWhat is wind?What causes windto form?

ObjectiveAt the end of class, you will be able to:Relate air pressure and wind directionExplain why winds flow in a curved directionDiscern global winds from local windsDescribe the three main global wind patterns on EarthExplain two types of local wind patterns

Terms to KnowWindCoriolis effectJet stream

Trade windsWesterliesPolar easterliesWhat is Wind?Wind is air in motion.Formed by differences in pressureCaused by uneven heating of the atmosphereLaw of diffusion: moves from high to lowGreater pressure difference = faster winds

Where the Wind Blows

HLCheckpoint 1Why doesnt wind blow directly from the poles to the equator?Checkpoint 1Why doesnt wind blow directly from the poles to the equator?

Thought to consider: is the Earth in a fixed position?The Coriolis EffectWind movement affected by Earths rotationResults in a curved path of motionDepends on hemisphere you are inNorthern hemisphere- winds curve to the rightSouthern hemisphere- winds curve to the left

Recap: Coriolis EffectThe Coriolis effect is the curving motion of objects caused by the Earths rotation

Types of WindGlobal windsPattern of circulation across the EarthTravel great distancesTravel in a specific directionLocal windsTravel short distancesCan blow from any directionGlobal Wind PatternsTrade WindsWesterliesPolar EasterliesDoldrumsHorse Lattitudes

Checkpoint 2What do you think may cause global wind patterns?Checkpoint 2What 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?Pressure Belts Explain Global Wind PatternsHigh pressure belts near 30oN, 30oSLow pressure belts near 60oN, 60oSResult in patterns of rising and sinking airSounds familiarConvection?

What are Jet Streams?Jet stream- narrow belt of high speed windsFound in upper troposhere, lower stratosphereDo not follow regular patternsChange positions frequentlyAffect weather movementLocal WindsLocal winds are affected by an areas geographyResults in wind blowing from any directionExamples:Sea breezeLand breezeSea Breeze

Land Breeze

Checkpoint 3Why 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?