Sunday, October 4, 2009
The Great Deserts-Were they Man Made(destruction of nature)
or was it a part of Creation of the Creator?
www.youtube.com/watch?v=7QRYtBeQo7Q
The 10 largest deserts Rank ↓ Desert ↓ Area (km²) ↓ Area (mi²)
↓
1 Antarctic Desert (Antarctica) 13,829,430 5,339,573
2 Arctic 13,700,000+ 5,300,000+
3 Sahara (Africa) 9,100,000+ 3,320,000+
4 Arabian Desert (Middle East) 2,330,000 900,000
5 Gobi Desert (Asia) 1,300,000 500,000
6 Kalahari Desert (Africa) 900,000 360,000
7 Patagonian Desert (South America) 670,000 260,000
8 Great Victoria Desert (Australia) 647,000 250,000
9 Syrian Desert (Middle East) 520,000 200,000
10 Great Basin Desert (North America) 492,000 190,000
A desert is a landscape or region that receives almost no precipitation. Deserts are defined as areas with an average annual precipitation of less than 250 millimetres (10 in) per year, or as areas where more water is lost by evapotranspiration than falls as precipitation.
In the Köppen climate classification system, deserts are classed as BWh (hot desert) or BWk (temperate desert). In the Thornthwaite climate classification system, deserts would be classified as arid megathermal climates.
Deserts take up about one third (33 percent) of the Earth's land surface. Hot deserts usually have a large diurnal and seasonal temperature range, with high daytime temperatures, and low nighttime temperatures (due to extremely low humidity). In hot deserts the temperature in the daytime can reach 45 °C/113 °F or higher in the summer, and dip to 0 °C/32°F or lower in the winter. Water acts to trap infrared radiation from both the sun and the ground, and dry desert air is incapable of blocking sunlight during the day or trapping heat during the night.
Thus, during daylight most of the sun's heat reaches the ground, and as soon as the sun sets the desert cools quickly by radiating its heat into space. Urban areas in deserts lack large (more than 14 °C/25 °F) daily temperature variations, partially due to the urban heat island effect.
Many deserts are formed by rain shadows; mountains blocking the path of precipitation to the desert (on the lee side of the mountain). Deserts are often composed of sand and rocky surfaces. Sand dunes called ergs and stony surfaces called hamada surfaces compose a minority of desert surfaces. Exposures of rocky terrain are typical, and reflect minimal soil development and sparseness of vegetation. The soil is rocky because of the low chemical weathering.
http://www.youtube.com/watch?v=zmQub8NDkTI-TODAY SPECIAL
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