Winter weather has returned to northern areas of the world. In much of the United States, winter means the return of snow. Snow is a form of frozen water. It contains many groups of tiny ice particles ( ) called snow crystals ( ) . These crystals grow from water particles in cold clouds. They usually grow around a piece of dust. All snow crystals have six sides, but they grow in different shapes. The shape depends mainly on the temperature and water levels in the air. The shape of a snow crystal may change from one form to another as the crystal passes through levels of air with different temperatures. Snow contains much less water than rain. About seventy-five centimeters of snow has as much water as two and one-half centimeters of rain. Generally, the color1 of snow and ice appears white. This is because the light we see from the sun is white. Most natural materials take in some sunlight. However, when light travels from air to snow, some light is sent back, or reflected ( ). Snow crystals have many surfaces to reflect sunlight. It is this light that gives snow its white color1. Much of the water we use comes from snow. Melting snow gives water to rivers and crops. Snowfall helps to protect plants and some wild animals from cold. Fresh snow is made largely of air which is kept among the snow crystals. Because the air has trouble moving, the movement of heat is greatly reduced. However, snow is responsible for the deaths of hundreds of people in the United States every year. Many people die in traffic accidents on roads that are covered with snow or ice. How can snow protect plants from the cold?
It gives them much heat. It has a higher temperature. It keeps them from wind. It contains air which helps hold heat.