Winds Wind is the horizontal movement of air.

Air always moves from H L pressure.

Temperature differences create pressure differences.

Weather is based on the unequal heating of Earth’s surfaces. Some surfaces heat up more than others. This warms up the air and causes pressure differences …

Local Winds: Sea & Land Breezes

http://www.classzone.com/books/earth_science/terc/content/visualizations/es1903/es1903page01.cfm?chapter_no=visualization

Local Breezes – over short distancesEx.: Sea breezes – happen during the day because LAND Heats Up FASTER THAN WATER (water takes a long time to heat up and cool down).

Local Breezes – over short distancesEx.: Land breezes – happen at night because LAND COOLS DOWN FASTER THAN WATER.

Air is mostly heated by I.R. re-radiated off of surfaces. Warmer surfaces Warmer air Less dense (more expanded) Low PressureCooler surfaces Cooler air Denser High PressureWind moves from H L pressure

Air is mostly heated by I.R. re-radiated off of surfaces. Warmer surfaces Warmer air Less dense (more expanded) Low PressureCooler surfaces Cooler air Denser High PressureWind moves from H L pressure

Local Breezes – over short distancesEx.: Land breezes – happen at night because LAND COOLS DOWN FASTER THAN WATER.

Warm air •More Kinetic Energy •Less Dense•Low Pressure•Rises (less dense)•Room for moisture

Cold air •Less Kinetic Energy •Denser•High Pressure•Sinks(denser)•Dry (less room for moisture)

MOONSOON RAINS are seasonal and experienced in India & S.E. Asia (subtropical locations)

Summer – Land is warmer (Low Pressure) than Water (High Pressure). Air moves from water to land carrying moisture --- RAIN.

It can rain 37 ft of rain in a few months.

Remember … Land heats up faster than water.

Winter – Land is cooler than water. Air moves from land to water – this is a DRY SEASON

Regional Winds: Monsoon Winds

Regional Wind Patterns: El Nino & La Nina

Natural short range change in climate due to change in wind pattern and ocean currents.

El Nino: Periodic warming of water in the central & eastern Pacific Ocean (off coast of Peru)

Normally this water is VERY COLD due to an upwelling from the deep ocean.

• Warm water warmer air Less Pressure = trade winds slacken or weaken

• Ocean currents in Pacific weaken or reverse direction (b/c trade winds weaken)

Result: Abnormal weather (Rain on West Coast; Milder Winter on East coast; more Drought in Austrialia, and S.E Asia

When: Every 8 yrs (average)

Normal Years

Cold water off S. America High pressure air = Trade Winds blow AWAY from S. America across Pacific (Dry air in Western Americas)

El Nino Years

Warmer water off S. America Less High pressure air = Trade Winds WEAKEN or reverse

Changes what locations get rain/snow/or draught

El Nino year

La Nina – cooler water El Nino– Warmer water

La Nina = Opposite of El NinoYear when the cold current off the coast of S. America is “extra” cool.

Air off coast of S. America = High Pressure

GLOBAL WINDS – DUE TO DIFF. IN PRESSURE

Warm air rises at the equator and cold dense air sinks at the poles. In general wind want to move from Poles Equator, but E’s rotation CURVES the path of wind.

CORIOLIS EFFECT – DUE TO EARTH’S ROTATION, CURVES THE PATH OF THE WIND.

Wind & Surface Currents deflect TO THE RIGHT in the N. Hemi; TO THE LEFT in the S. Hemi.

WARM AIR RISES – LOW PRESSURE

COOL AIR SINKS – HIGH PRESSURE

http://www.classzone.com/books/earth_science/terc/content/visualizations/es1905/es1905page01.cfm?chapter_no=visualization

http://www.mhhe.com/biosci/genbio/tlw3/eBridge/Chp29/animations/ch29/global_wind_circulation.swf

Global Winds

http://www.coolschool.ca/lor/GEO12/unit9/U09L03.htm

Global Winds: Warm Low Pressure Air (carrying moisture) Rises @ Equator and Sinks @ 30 N & S (dry, sinking, high pressure air)

http://www.ukdivers.net/meteorology/coriolis.htm

Global Winds: There are 3 major convection cells of rising and sinking air for each hemisphere.

Due to Coriolis: Air deflects to the Right in the N. Hemi. And to the Left in the S. Hemi.

Remember: start at the BASE of the arrow.

Winds Aloft (high in Troposphere)JET STREAM – •Rivers of high speed wind at the top of the troposphere.•Separates cold Canadian air from warm Gulf air.•Steers weather.

• When jet stream dips south, NJ gets cold Canadian air.• When jet streams moves north, NJ gets warm Gulf air.

Jet Stream:http://www.wunderground.com/US/Region/US/pxJetStream.html

http://www.pbs.org/wgbh/nova/vanished/jetstr_giving.html

Current Jet Stream Animations:http://www.wunderground.com/global/Region/EU/pxJetStream.html