One-fifth of the Earth's land is covered by Deserts and in every continent they are found .In this region one-sixth of the Earth's population that is about more than one billion people actually are living there .Only about 10% of the deserts have sand dunes. There are two types of deserts : 1- Hot deserts 2- Cold deserts Hot Deserts: * The largest hot desert in the world is Sahara Desert. * The temperature there rises up to 50 degrees Celsius during the day but in the night it reaches up to -18 degree Celsius . * About 250 millimeters of rainfalls per year. * Animals like Camels are adapted in such a way that they can go without food and water for many days. Many of anim...