Transcript Wind
Wind Mr. Parr on Wind Wind • Horizontally moving air; cause by uneven heating of the Earth’s surface, which creates warm and cool air masses, resulting in differences in air pressure from place to place; moves from high pressure area to low pressure area, like when deflating a balloon Gust • A brief sudden increase in wind speed Local Wind • Moves across small distances close to Earth’s surface; unpredictable; changes frequently with air pressure fluctuaton (ex. Sea breeze, land breeze, Chinook, Santa Ana, etc.) Global Wind • Moves great distances over the globe; predictable and stable; also called atmospheric circulation (ex. Polar Easterlies, Prevailing Westerlies, Trade Winds) Trade Winds • Winds that occur between 30 N and 30 S, blow from East to West; Blows continuously toward the Equator, global winds Prevailing Wind • A wind that usually blows from one direction (ex. West to east) Prevailing Westerlies • Winds that occur between 30 and 60 in both hemispheres; blow from west to east; blow towards the poles Polar Easterlies • Winds that occur between 60 and 90 in both hemispheres; blow from east to west; blow away from poles Wind Chill • The “feel like” temperature on a cold day when you factor in the winds Jet Stream • A strong wind found 6-9 miles up in the troposphere. A jet stream can reach speeds of ~50-200 mph. Jet streams steer the movement of air masses and weather systems. Above North America the jet stream moves weather from West to East. It can change locations on global conditions. Learn Some More… • http://www.weatherwizkids.com/weatherwind.htm Sea Breeze • A convection current where air flows from sea to land during the daytime; a local wind (land heats up and cools down faster than water) Land Breeze • A convection current where air flows from land to sea during the nighttime; a local wind (land heats up and cools down faster than water) Watch This… • Check out this animation of land and sea breeze • http://www.classzone.com/books/earth_sci ence/terc/content/visualizations/es1903/es 1903page01.cfm Sea • vs. During the day, land gets heated by the Sun much quicker than water. As the land becomes warmer, it heats the air in the atmosphere above it. This causes the air to expand, becoming less dense, creating a low pressure. Water heats up less quickly, air above the ocean also takes longer to increase in temperature. A higher pressure is maintained. With a high pressure above the water and a lower pressure above the land, conditions are perfect for a small breeze to develop. Wind blows from the sea towards the land along the pressure gradient in an attempt to equalize pressure. Land • In the night, land cools down much quicker than does the waters of the ocean. As the land becomes cooler, so does the air above it. This results in air becoming more dense, forming a high pressure, causing winds to blow outward towards the sea.