Secrets of the Desert: Earth's Driest Biome

Imagine going for a whole year without a single drop of rain. No puddles, no muddy boots, no wet umbrellas — just dry, cracked ground as far as you can see. Some places on Earth are really like this. They are called deserts. Before you read on, think about this: when you picture a desert, what do you see? Sandy dunes? Blazing sun? You might be surprised — not all deserts are hot!

A biome is a large area of the world that shares the same climate, plants, and animals. The desert biome is defined by one thing above all else: very little rain. Scientists call a place a desert if it gets less than 250 mm of rain per year — that is less water than in a small bottle of juice. Deserts cover about one third of Earth's land surface. They are found on every continent, including Antarctica. Most people think of hot deserts first. The Sahara Desert in northern Africa is the world's largest hot desert. Daytime temperatures there can reach 50 °C. Nights can actually be very cold because there are no clouds to keep the warmth in. But there are also cold deserts. The Gobi Desert in central Asia is a cold desert. Temperatures there can drop far below freezing in winter. Antarctica is also counted as a desert because almost no rain or snow falls there, even though it is covered in ice. Desert plants and animals have special features that help them survive with almost no water. A cactus stores water inside its thick stem. The camel stores energy in its hump as fat, which helps it go many days without food or water. Many desert animals come out only at night, when it is cooler, to save water from their bodies.