Wednesday, July 10, 2013

Literature Review (Wun Juan)

Project Title: An investigation on how wind speed affect how quickly an object cools

Wind

Wind is simply air in motion. It is caused by the uneven heating of the Earth’s surface by radiant energy from the sun. Earth’s surface is made of very different types of land and water, so 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.

Wind Speed

Wind speed can be measured using a anemometer. One type of 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

A phenomenon called the Wind Chill factor makes us feel colder in winter than the air temperature really is. This is due to the interaction of air temperature and wind on the human body that is already giving off heat. Both temperature and wind cause heat loss from body surfaces. A combination of cold and wind makes a body feel colder than the actual temperature.
References: 

Wind Energy, (2012). Retrieved July 10, 2013, from http://www.need.org/needpdf/infobook_activities/IntInfo/WindI.pdf


James P. Dildine, Brrrr....Wind Chill is Chilly (1999). Retrieved July 10, 2013, from http://mste.illinois.edu/dildine/wind_chill/#contact

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