Academic Reading
The world's deserts
AA desert is defined not by heat but by dryness: any region that receives very little rainfall, usually less than 250 millimetres a year, counts as a desert. This means that some deserts, such as parts of Antarctica, are extremely cold.
BDespite their harsh conditions, deserts are far from lifeless. Plants and animals have evolved remarkable adaptations to survive, from the water-storing stems of cacti to creatures that are active only at night to avoid the fierce daytime heat. The largest hot desert on Earth is the Sahara in North Africa.