The part of the earth’s surface where, at temperatures below 32°F (0°C), the water is frozen solid. Even a small pond while frozen over during the winter is part of the cryosphere, but cryosphere refers more often to large regions covered in snow and ice for much or all of the year, as the ice sheets of Antarctica and Greenland, glaciers, icebergs, and expanses of permafrost, all of which are especially sensitive to global shifts in climate:
