15 3 Global Winds and Local Winds Why

15. 3 Global Winds and Local Winds

Why Air Moves • Wind-movement of air caused by differences in air pressure • Greater pressure difference=faster wind

Air Rises at the Equator and Sinks at the Poles • Equator – Receives more direct solar energy – Air is warmer and less dense – Warm air rises and flows to poles

National geographic video clip • http: //video. nationalgeographic. com/video/ player/science/earth-sci/weather-101 sci. html? referrer=epals

Air Rises at the Equator and Sinks at the Poles, cont’d • Poles – Air is cooler and more dense – Cold air sinks – Cold air flows toward equator

Pressure Belts Are Found Every 30 Degrees • Pressure belts-bands of high pressure and low pressure found every 30 latitude. • Sinking air causes areas of high pressure because sinking air presses down on the air beneath it.

The Coriolis Effect • Apparent curving of the path of winds and ocean currents due to the Earth’s rotation. • North- winds going north curve east • South- winds going south curve west

Global Winds • Global Patterns of air circulation • Named from direction from which they blow • Major global wind systems – Polar easterlies – Westerlies – Trade winds

Global winds

Polar Easterlies • Poles to 60 latitude in both hemispheres • Cold, dense air moves from poles to 60 • Can bring cold air to US making snow and freezing weather

Westerlies • 30 and 60 latitude in both hemispheres • Flow from west to east • Can bring moist air to US making rain and snow

Trade Winds • 30 latitude almost to equator in both hemispheres • Due to Coriolis-curve to west in N. Hemisphere and east in S. Hemisphere • Traders used winds to move from Europe to Americas.

Doldrums • Area around equator where there is very little wind

The Horse Latitudes • 30 north and south latitude • Very weak winds

Jet Stream: Atmospheric Conveyor Belts • Narrow belts of high speed winds • Blow in the upper troposphere and lower stratosphere • Can affect movement of storms and airplane flights

Local Winds • • • Move short distances Blow from any direction Caused by temperature differences Sea breeze moves from sea to land Land breeze moves from land to sea

How does wind blow? • Wind will flow from high to low!!!

Wrapping it up • What role does the Sun play? – Sun heats the land water, changing temperatures – Different heating causes density differences, causing wind! – UNEQUAL HEATING CAUSES THE WIND!

Temperature of Coast vs. Inland • Avg temperature Atlanta: low-23 to 51: 28 degree difference for January • Avg temp. for Savannah: low-38 to 60: 22 degree difference • Avg for July: Atlanta-88 • Savannah- 92 • Why is Savannah warmer? – Gulf Stream runs by it and there is a constant breeze blowing near the ocean – Lower temp range on coast

Temperature of Coast vs. Inland • Coastal areas don’t get as warm or as cold as inland areas because it has the ocean to moderate their temperatures.