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A powerpoint on deserts for my school assessment. I love butterflies and flowers.

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  1. 1. Deserts By Tom Hyatt
  2. 2. Facts  For a place to be considered as a desert it has to have a yearly rainfall of 10 inches or less.  Antarctica is the largest desert on Earth even though it is cold and icy.  The Sahara is the hottest desert on Earth and has an average yearly rainfall of 3.9 inches.  Deserts cover about 1/5th of the Earths surface.  There are five major types of deserts, dry, hot, semiarid, coastal and cold.
  3. 3. Formation  Deserts are formed when a place receives minimal amounts of precipitation.  Some deserts can be found on the west coasts of continents right next to the ocean. Even though they are near water little precipitation occurs because the water is colder than on the east coast meaning the water is less likely to be evaporated.
  4. 4. Hot and Dry Deserts  The seasons are generally warm and very hot in the summer. Winter usually brings very little rainfall. Desert surfaces receive nearly twice as much solar radiation than humid environments and lose almost twice as much heat after the sun goes down.  Rainfall is usually very low and/or concentrated in short bursts between long rainless periods. Evaporation rates normally exceed rainfall rates.  The soil is course-textured and rocky/gravely and has no subsurface water. The reason for the dirt been so coarse is that the finer dust particles get blown away elsewhere leaving larger pieces of rock behind.
  5. 5. Semiarid Deserts  Summer is moderately long and dry. Like hot deserts winter brings very little rainfall. Summer temperatures average about 21-27˚C and normally does not go above 38˚C.  The average annual rainfall for semiarid deserts is 2-4cm. The condensation of dew at night may equal or exceed the rainfall received by some deserts.  The soil can range from sandy and fine-textured to loose rock fragments, gravel and sand. Semiarid deserts have no subsurface water whatsoever.
  6. 6. Cold Deserts  Cold deserts are recognised by cold winters and snowfall with high overall rainfall in the winter and occasionally in the summer. The winter temperature ranges from -2 to 4˚C and the summer temperature ranges from 21 to 26˚C.  In the winter there is quite a bit of snow and the most amount of rain is received in either April or May. The soil is heavy, silty and salty but due to good drainage there is only a little bit of salt.
  7. 7. Coastal Deserts  Coastal deserts are found in warm areas such as Nearctic and Netropical realms. Winter is very cold with 5˚C and below and is followed by a moderately long summer with temperatures ranging from 13-24˚C.  The average annual rainfall is 8-13cm in most areas. This low amount of rainfall makes the soil fine-textured with a moderate salt content. Some plants have long roots close to the surface so that they can take advantage of the low rainfall.
  8. 8. Climates  Deserts are places that have very minimal rainfall. People think that deserts are hot and dry places with sand everywhere but deserts climates are much more complex. They can be cold, icy, hot, dry, rocky and windy.  Deserts occur in places like the north and south poles, inland areas, coasts and sometimes in subtropical areas.
  9. 9. Desertification  Desertification is the process by which fertile land becomes desert, typically as a result of drought, deforestation, or overuse of land for agriculture.
  10. 10. Locations
  11. 11. Underground Water  In some deserts there is a layer of rock that stores water, this is called an aquifer. When you see an oasis in the desert the water is coming from the aquifer and supplying the plants with water.
  12. 12. Flora and Fauna  There are many special and interesting types of plants and animals that inhabit deserts. These plants and animals have evolved over time so they are able to survive in the harsh conditions of a desert.
  13. 13. Landforms  When you think of a deserts you think of sand dunes but did you know that there are lots of different types of sand dunes and desert landforms. Some of these include, pedestal rocks, star dunes, barchan dunes, mesas and inselbergs.
  14. 14. Size Comparisons
  15. 15. Bibliography  biome/deserts.html  on.htm  te_map.gif   Global Explorations Stage 4 Geography 