• Question: Why does it never rain in the Sahara Desert, is the only reason becuase it is too hot?

    Asked by lozsciencegleek to MarkF, Mark, Michael, Panos, Sarah on 22 Jun 2010 in Categories: .
    • Photo: Sarah Burl

      Sarah Burl answered on 22 Jun 2010:

      The Sahara does get some, about 5-10inches a year! As far as I am aware the hot air rises and before it cools and condenses to rain it is dispersed so there are never clouds formed. The desert is very hot in the day but very cold in the night because there are no clouds to stop it and nothing in the desert to absorb the heat.

    • Photo: Mark Fogg

      Mark Fogg answered on 22 Jun 2010:

      I’d need to research this for more detail but will attempt to answer off the top of my head, Geography and Geology were my wife’s subject. 😉
      It does actually rain occasionally in the Sahara, averaging a few mm/Year only, just not as much as the non dessert land around it.

      Desserts are formed by a combination of local Geography/Geology and prevailing weather systems.

      There are far drier places than the Sahara where it hasn’t rained for years, such as the Atacama dessert in south America. I think parts of it have gone through periods where it hasn’t rained for HUNDREDS of years. The Atacama is only the second driest on Earth, the driest being the McMurdo dry valleys in Antarctica, where they have even found some bacteria, living INSIDE rocks.

      Great NASA Atacama picture here

      http://www.nasa.gov/multimedia/imagegallery/image_feature_1536.html

      I had a chat with my wife (a former Geologist) about this recently, having watched an episode of Top Gear where the guys were driving across the Atacama Dessert. Mad! 😉

    • Photo: Michael Loughlin

      Michael Loughlin answered on 22 Jun 2010:

      Not really as other areas along the same line of the equator are quite lush…

      I found a gardening link that expalins to a degree…bear with me

      http://chestofbooks.com/gardening-horticulture/Journal-3/What-Makes-A-Desert.html

      it is more to do with weather and geography…what is useful is nice moisture full air rising over a mountain range to deposit rain…
      of course too high amountain or too much ice will suck out the moisture
      so the quick answer is geography ( mountains) temperature and once you get a lack of vegetation you then have few ways to keep any rain that does fall. Thats how deserts grow with deforeststaion, topsoil has nopthing to hang onto is and is literally blown away living bedrock to be turned to sand over time

      good question..thanks made me think

    • Photo: Panos Soultanas

      Panos Soultanas answered on 22 Jun 2010:

      It does rain the sahara desert but the rainfall is small relatively to other places. Sahara wasnot always a desert. Major climatic changes a very long time ago resulted in the desert. There is some evidence now that the edges of the sahara are becoming greener because of increased rainfall. his because of global warming.Hotter air has more capacity to hold moisture, which in turn creates more rain.

      There is a very good BBC website to read about the climate of the sahara and how it was formed.

      http://news.bbc.co.uk/1/hi/sci/tech/390097.stm

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