Snow is frozen precipitation, formed from ice crystals within clouds. Snow is normally pure, and like rain, provides a supply of fresh water. In cold climates, snow can compact and refreeze into ice, forming massive glaciers as in Antarctica. Normally snow falls in winter. It may be produced in large quantities from moist air that is rapidly pushed to a higher altitude, or from very moist air over large bodies of water. Snow is usually annoying to adults because it is cold, and sticks to surfaces and wets them. Snow accumulations have to be removed from houses and roads. Kids enjoy playing with the snow because it will usually clump together. Snow can be made into snowballs and snow forts, for snow fights, or rolled into larger balls to form snowmen and other figures. Snow is recreationally used in skiing, sledding, snowboarding, and with snowmobiles.