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Questions of the Day • Describe how wind is created. • What happens to air pressure as I hike up a mountain? • What instrument measures air pressure? Global and Local Winds Air Movement •Wind is the movement of air caused by differences in air pressure •The greater the difference, the faster the wind moves Air Pressure •Differences in air pressure are caused by the uneven heating of Earth •Uneven heating produces pressure belts which occur every 30° latitude Pressure Belts •As warm air rises at the equator and moves toward the poles, it cools •As it cools, some of the air sinks around 30° north and south of the equator Pressure Belts •At the poles, cold air sinks and moves towards the equator •Around 60° north and south, the air begins to heat up and rise Coriolis Effect • Because the Earth rotates, and consists of a mixture of land and sea, the Coriolis Effect exists • The Coriolis Effect is the movement of particles (such as air) to the right in the Northern Hemisphere • How about the South? – They move to the left Coriolis Effect Coriolis Effect • Coriolis Effect – Rotation of the Earth causes moving air and water to change directions • Northern Hemisphere winds curve to the right • Southern Hemisphere winds curve to the left. http://www.youtube.com/watch?v=mcPs_OdQOYU Global Winds •The combination of pressure belts and the Coriolis Effect cause global winds •These are polar easterlies, prevailing westerlies, and trade winds Warm Moist Air Rises Cool Dry Air Sinks Warm Moist Air Rises Cool Dry Air Sinks Cold Moist Air Rises Cool Dry Air Sinks Warm Moist Air Rises Cool Dry Air Sinks Cold Moist Air Rises Very Cold Air Sinks Cold Moist Air Rises Cool Dry Air Sinks Warm Moist Air Rises Cool Dry Air Sinks Cold Moist Air Rises Very Cold Air Sinks Very Cold Air Sinks H Cold Moist Air Rises L H Cool Dry Air Sinks L Warm Moist Air Rises Cool Dry Air Sinks Cold Moist Air Rises Very Cold Air Sinks H H L H L H L H L H Wind Moves from HIGH to LOW Objects are deflected to the RIGHT in the Northern Hemisphere Polar Easterlies •Wind belts that extend from the poles to 60° latitude •Formed from cold sinking air moving from the poles creating cold temperatures Prevailing Westerlies •Wind belts found between 30° and 60° latitude •Flow towards the poles from west to east carrying moist air over the United States Trade Winds •Winds that blow from 30° almost to the equator •Called the trade winds because of their use by early sailors Doldrums •Located along the equator where no winds blow because the warm rising air creates and area of low pressure Horse Latitudes • Occur at about 30° north and south of the equator where the winds are very weak • Most deserts on the Earth are located here because of the dry air Jet Stream •The jet streams are narrow belts of high speed winds that blow in the upper troposphere and lower stratosphere •Separates warm air from cold air Jet Streams • Jet Streams form at • latitudes where wind systems come together High speed westerly winds form high above the surface What brings certain weather phenomenon? El Nino • occurs when the surface temperature rises above the normal water temperature in the Equatorial Pacific Ocean creating more humidity in the atmosphere • Known to increase number of hurricanes • Occur more frequently (every 3-7 years) La Nina occurs when the surface temperature falls below the normal water temperature in the Equatorial Pacific Ocean creating a more dry atmosphere Known to create drought conditions Local Winds •Generally move short distances and can blow in any direction •Caused by geographic features that produce temperature differences Local Winds • Cover short distances • Blow from any direction • 2 Types of Local Winds – Sea Breezes- from sea to land – Land Breezes – from land to sea Sea Breezes • High pressure is created over the ocean during the day and low pressure over land due to uneven heating • Air moves from the ocean to the land creating a sea Land Breezes • Low pressure occurs over the ocean during the night and high pressure over land due to the uneven heating of earth • This causes wind to move from the land to the ocean creating a land breeze What’s the difference? Question 1 •What causes winds? Answer •Winds are caused by the uneven heating of Earth’s surface, which causes pressure differences Question 2 •What are the three types of global winds? Answer •Polar Easterlies •Westerlies •Trade Winds Question 3 •What is the difference between a land breeze and a sea breeze? Answer •Sea breezes occur during the day when the land is warmer than water and a land breeze occurs at night when the water is warmer than land Global Wind Patterns Flipbook • Cut out the outline map. Set aside. • Fold 2 sheets of paper long ways in half • Cut both pieces in half long ways along the fold lines. Keep three strips of paper. • Stack the papers on top of each other. Global Wind Patterns Flipbook • Shift the papers over so that there is approximately one cm between each one • At the middle of the stack fold the papers under so that each tab is about a cm across • Staple • Glue outline map on front tab Global Wind Patterns Flipbook • Fill in an label the global wind patterns using the following colors. Use the same colors when writing the name of the wind on the tabs • Doldrums-red • Tradewinds-orange • Horse latitudes-yellow • Westerlies-green • Polar easterlies-blue Global Wind Patterns Flipbook • Draw arrows using black to indicate the directions of the winds movement due to the Coriolis Effect • On the tabs above each item (above the terms) give a detailed description of the concept