What Is Wind
Wind is the air in motion caused by the uneven heating of the Earth’s surface by radiant energy from the sun. Since the Earth’s surface is made of very different types of land and water, it absorbs the sun’s energy at different rates. Water usually does not heat or cool as quickly as land because of its physical properties.
An ideal situation for the formation of local wind is an area where land and water meet. During the day, the air above the land heats up more quickly than the air above water. The warm air over the land expands, becomes less dense and rises.
The heavier, denser, cool air over the water flows in to take its place, creating wind. In the same way, the atmospheric winds that circle the Earth are created because the land near the equator is heated more by the sun than land near the North and South Poles. Today, people use wind energy to make electricity. Wind is called a renewable energy source because the wind will blow as long as the sun shines.
It is important in many cases to know how fast the wind is blowing. Wind speed can be measured using a wind gauge or anemometer. An anemometer is a device with three arms that spin on top of a shaft. Each arm has a cup on its end. The cups catch the wind and spin the shaft. The harder the wind blows, the faster the shaft spins. A device inside counts the number of rotations per minute and converts that figure into miles per hour. A display on the anemometer shows the speed of the wind.
Wind Chill Factor
When the wind blows across the exposed surface of our skin, it draws heat away from our bodies. When the wind picks up speed, it draws more heat away, so if your skin is exposed to the wind, your body will cool more quickly than it would have on a still day.
The actual formula for wind chill. Just in case you ever find yourself with a calculator, thermometer, and anemometer but without access to The Weather Channel, the Fahrenheit version of the equation looks like this:
Wind Chill = 35.74 + 0.6215T "“ 35.75(V^0.16) + 0.4275T(V^0.16)
T is the air temperature in degrees Fahrenheit, and V is the wind speed in miles per hour.
Bibliography
Ethan Trex. (December 27, 2010). Mental Floss. In How Is Wind Chill Calculated?. Retrieved July 10, 2013, from http://mentalfloss.com/article/26730/how-wind-chill-calculated
need.org (2012). National Energy Education. In Wind Energy. Retrieved July 10, 2013, from http://www.need.org/needpdf/infobook_activities/IntInfo/WindI.pdf
