16 Remote Sensing of Cryosphere Shrinidhi Ambinakudige and Kabindra Joshi Mississippi State University USA 1. Introduction The cryosphere is the frozen water part of the Earth’s system. The word is derived from the Greek “kryos,” meaning cold. Snow and ice are the main ingredients of the cryosphere and may be found in many forms, including snow cover, sea ice, freshwater ice, permafrost, and continental ice masses such as glaciers and ice sheets. Snow is precipitation made up of ice particles formed mainly by sublimation (NSIDC, 2011). Ice is the key element in glaciers, ice sheets, ice shelves and frozen ground. Sea ice forms when the ocean water temperature falls below freezing. Permafrost occurs when the ground is frozen for a long period of time, at least two years below 0 0 C, and varies in thickness from several meters to thousands of meters (NSIDC, 2011). Glaciers are thick masses of ice on land that are caused by many seasons of snowfall. Glaciers move under their own weight, the external effect of gravity, and physical and chemical changes. The cryosphere lowers the earth’s surface temperature by reflecting a large amount of sunlight, stores fresh water for millions of people, and provides habitat for many plants and animals. Apart from the Arctic and Antarctic regions, the cryosphere is mainly a high altitude phenomenon. It is found on Mount Kilimanjaro in Africa, the Himalayan mountain range, high mountains of United States, and in Canada, Russia, Japan, and China. Researchers in the cryosphere are often hindered by the lack of accessibility due to the rugged terrain. In such cases, remote sensing technologies play an important role in cryosphere research. These techniques are imperative for researchers studying glacial retreat and mass balance change in relation to global climate change. The cryosphere has a significant influence on global climate and human livelihoods. Change in spatial and temporal distribution of the cryosphere influences the water flow in the world’s major rivers. Among the various parts of the cryosphere, glaciers play the most important role in climate change studies since glacier recessions are indicators of global climate change (Oerlemans et al., 1998; Wessels et al., 2002; Ambinakudige, 2010). Retreating glaciers can pose significant hazards to people (Kaab et al., 2002). Glacier retreat often lead to the formation of glacial lakes at high altitudes, the expansion of existing lakes, and the potential for glacial lake outburst floods (GLOFs) (Fujita et al., 2001; Bajracharya et al., 2007). A GLOF is the sudden discharge of a huge volume of water stored in a glacial lake due to huge ice falls, earthquakes, avalanches, rock fall or failure of a moraine dam (Grabs & Hanisch, 1993). There are more than 15,000 glaciers and 9,000 glacial lakes in the Himalayan mountain ranges of Bhutan, Nepal, Pakistan, China and India (Bajracharya et al., 2007). All www.intechopen.com