Wind SystemsWind Systems

Grade 8Grade 8Earth ScienceEarth Science

WindWind Movement of air from an area of high Movement of air from an area of high

pressure to an area of low pressurepressure to an area of low pressure Winds are named by their direction Winds are named by their direction

of originof origin

Wind SystemsWind Systems Series of Global Winds created by Series of Global Winds created by

Convection Currents and the Coriolis Convection Currents and the Coriolis EffectEffect

Global WindsGlobal Winds

Doldrums

DoldrumsEquator

Global Winds Caused byGlobal Winds Caused by Convection Cycles Convection Cycles

Coriolis EffectCoriolis Effect The Earth is spinning on its axis once The Earth is spinning on its axis once

every 24 hours.every 24 hours. So when the cold dense air come So when the cold dense air come

down from the convection cycle the down from the convection cycle the appear to “bend”appear to “bend”

DoldrumsDoldrums Windless zone at the equatorWindless zone at the equator

Global WindsGlobal Winds

Doldrums

DoldrumsEquator

Trade WindsTrade Winds Winds used to bring the “Trade” from Winds used to bring the “Trade” from

England to AmericaEngland to America

Global WindsGlobal Winds

Doldrums

DoldrumsEquator

Prevailing WesterliesPrevailing Westerlies Winds used when sailing back to Winds used when sailing back to

England from AmericaEngland from America Winds that are responsible for most Winds that are responsible for most

of our weatherof our weather

Global WindsGlobal Winds

Doldrums

DoldrumsEquator

Polar EasterliesPolar Easterlies Winds at the PolesWinds at the Poles

Global WindsGlobal Winds

Doldrums

DoldrumsEquator

Jet StreamsJet Streams The “Rivers of the Sky”The “Rivers of the Sky” Narrow belts of wind located in the Narrow belts of wind located in the

atmosphereatmosphere Greatly affect the movement of Air Greatly affect the movement of Air

MassesMasses