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Title: Gone With the Wind Reading Passage Wind is air in motion. It is caused by horizontal variations in air pressure. The greater the difference in air pressure between any two places at the same altitude, the stronger the wind will be. The wind direction is the direction from which the wind is blowing. A north wind blows from the north and a south wind blows from the south. The prevailing wind is the wind direction most often observed during a given time period. Wind speed is the rate at which the air moves past a stationary point. Winds and storms made the South Atlantic impossible to sail. All ocean sailors, before 1400, depended upon highly predictable seasonal winds and currents. These winds , also known as “trade winds,” were named such because when they blew, the traders sailed into, or out of, harbors. Trade winds and currents were the reason for regular long distance travel in the Pacific and Indian Oceans. A variety of instruments measure the wind. A wind vane measures the wind direction. Most wind vanes consists of a long arrow with a tail that moves freely on a vertical shaft. The arrow points into the wind and gives the wind direction. Anemometers measure wind speed. Most anemometers consist of three or more cups that spin horizontally on a vertical point. The rate at which the cups rotate is related to the speed of the wind. |
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