Discontinuous layer of water at or near the Earth's surface. It includes all liquid and frozen surface waters, groundwater held in soil and rock, and atmospheric water vapour. Virtually all of these waters are in constant circulation through the hydrologic cycle. Although the components of the hydrosphere are undergoing continuous change of state and location, the total water budget remains in balance. The components of the hydrosphere have been seriously affected by the water-polluting activities of modern society.