Major snow-prone areas include the polar regions, the northernmost half of the Northern Hemisphere, and mountainous regions worldwide with sufficient moisture and cold temperatures. In the Southern Hemisphere, snow is confined primarily to mountainous areas, apart from Antarctica. Snow affects such human activities as transportation: creating the need for keeping roadways, wings, and windows clear; agriculture: providing water to crops and safeguarding livestock; sports such as skiing, snowboarding, and snowmachine travel; and warfare. Snow affects ecosystems, as well, by providing an insulating layer during winter under which plants and animals are able to survive the cold.