The document discusses different types of deserts around the world. It defines a desert as a region receiving less than 25cm of rain annually and notes that deserts cover about one-fifth to one-third of the Earth's surface. The main types of deserts discussed are trade wind deserts like the Sahara, midlatitude deserts like the Sonoran, rain shadow deserts like the Turpan Depression, coastal deserts like the Atacama, monsoon deserts like the Thar, and polar deserts like the Dry Valleys of Antarctica. The Sahara Desert is highlighted as the largest hot desert, occupying 10% of Africa with average temperatures over 30°C.

1. LIFE IN DESERTS

2. About Deserts
• Definition - desert is a region that receives less
than 25cm of rain a year on average
• Only 15% of the world' s desert surface is pure
sand. (Parts of the Sahara and Arabia desert)
• Desert occupies about one fifth to one third of
the earth' s surface.
• The rate of evaporation ( known as " Moisture
Index" ) can be used to classify deserts as there
are extremely high temperatures, low humidities
and very little cloud cover

3. Image of a Deserts

4. Ripples on a dune in Mexico

5. Types of Deserts
• Trade wind deserts - The world's largest desert,
the Sahara of North Africa, which has
experienced temperatures as high as 57° C, is a
trade wind desert
• Midlatitude deserts - The Sonoran Desert of
southwestern North America is a typical
midlatitude desert.
• Rain shadow deserts - Turpan Depression in the
rain shadow desert of the Tian Shan of China
• Coastal deserts - A coastal desert, the Atacama of
South America, is the Earth's driest desert.

6. Types of Deserts -contd
• Monsoon deserts - The Rajasthan Desert of India
and the Thar Desert of Pakistan are parts of a
monsoon desert region
• Polar deserts - The Dry Valleys of Antarctica have
been ice-free for thousands of years
• Paleodeserts - Nebraska Sand Hills paleodesert
shows a well-preserved crescent-shaped dune (or
barchan) about 60 to 75 meters high.
• Extraterrestrial deserts - Mars is the only other
planet on which we have identified wind-shaped
(eolian) features

7. SAHARA DESERT – Location & General Description
• The Sahara Desert is the largest hot desert in the
world and occupies approximately ten percent of the
African continent with mean annual temperatures
exceeding 30°C.
• From the Atlantic Ocean in the west, the greater
Sahara stretches across Africa to the Red Sea and
down to the highlands of Ethiopia
• The Sahara is also extremely windy. Hot, dust-filled
winds create dust devils which can make the
temperatures seem even hotter.