Transcript Wind PPT
Wind EQ: What is wind? Wind is air in motion. It is produced by the uneven heating of the earth’s surface by the sun. Since the earth’s surface is made of various land and water formations, it absorbs the sun’s radiation unevenly. 2 factors are necessary to describe wind: speed and direction. What causes wind? As the sun warms the Earth's surface, the atmosphere warms too. Some parts of the Earth receive direct rays from the sun all year and are always warm. Other places receive indirect rays, so the climate is colder. Warm air, which weighs less than cold air, rises. Then cool air moves in and replaces the rising warm air. This movement of air is what makes the wind blow. How can the wind be harmful? Wind can be harmful when it brings: thunderstorms hurricanes tornadoes What are the tools used to measure the wind? How can we tell the direction of the wind? An anemometer measures the wind speed. It is made up of propeller cups which are rotated by the motion of the wind. A weather vane or wind vane tells the direction wind is blowing. What is the difference between local and prevailing winds? Local Winds Local winds depend on local changes in temperature. They affect only a small area of land. Sea Breeze- A type of local wind On a warm summer day along the coast, different heating of land and sea leads to the development of local winds called sea breezes. As air above the land surface is heated by radiation from the Sun, it expands and begins to rise, being lighter than the surrounding air. To replace the rising air, cooler air is drawn in from above the surface of the sea. This is how a sea breeze is formed. Land Breeze- A type of local wind A land breeze occurs at night when the land cools faster than the sea. In this case, it is air above the warmer surface water that is heated and rises, pulling in air from the cooler land surface. Local Winds See a Land and Sea Breeze in action! • http://www.oceanservice.noaa.gov/education/pd/ocean s_weather_climate/media/sea_and_land_breeze.swf • http://www.classzone.com/books/earth_science/terc/c ontent/visualizations/es1903/es1903page01.cfm Global Wind Patterns Global winds are caused by uneven heating of large parts of Earth’s atmosphere and by its rotation. These can be called many different names. Trade winds The trade winds are just air movements toward the equator. They are warm, steady breezes that blow almost continuously. Jet Streams Jet streams are fast flowing, currents of air found in the atmosphere at around 12 km above the surface of the Earth. Let’s see it https://www.youtube.com/watch?v=C_HiBj0t eRY The stream over the US flows west to east. Look again: https://www.windyty.com/?150h,2016-01-1406,40.441,-14.714,2 Jet Streams They form at the boundaries of adjacent air masses with significant differences in temperature What does this mean?? https://www.youtube.com/watch?v=CgM Wwx7Cll4 (Ask Dirk) https://www.youtube.com/watch?v=huw eohIh_Bw (Another view) Jet Streams Let’s try it out! Jet Streams What’s happening? Jet Streams What’s happening? Jet Streams What’s happening? Jet Streams What’s happening? sources http://www.weatherwizkids.com/wind1.htm http://upload.wikimedia.org/wikipedia/com mons/6/6d/Wind_vane_05643.jpg http://z.about.com/d/mandarin/1/0/f/c/-//windy_5.png http://teachers.henrico.k12.va.us/freeman/ kertis_j/Global%20and%20Local%20Wind s.ppt#260,5,Pressure Belts