Snow is formed by a lot of tiny crystals. 100 tiny crystals form one snow flake. Snow mainly falls in winter. In the South pole and North pole snow falls the whole year. People who live in the North pole and the South pole live in igloos. Snow covers 23 percent of the Earth's surface. A fun fact about snow is that if you put water on snow it will change into ice. Snow also affects climate as it makes the air cold.