Blues ranging from light to dark indicate snow depths ranging from deep to thin.
Sea ice is white, and glacier ice is purple.
Areas not covered by snow are brown. The snow pack is monitored by measuring the microwave radiation emitted and scattered by snow. Information about snow cover is important for a number of agricultural, industrial, social, and environmental reasons. For example, snow cover data are needed to predict water supply, to plan for agricultural and industrial developments, to anticipate flooding, to forecast crop yield, and to estimate freeze damage. Satellite data on snow cover also provide insights about regional climate and geography that have been used to develop military and foreign policy strategies.