ON THE LOGICAL FOUNDATIONS OF DIFFERENT INTERPRETATIONS OF THE “HYDROSPHERE” CONCEPT

The logical foundations of different interpretations of the fundamental “hydrosphere” concept, widely used in the Earth sciences, are discussed. Five principal interpretations of the hydrosphere notion were identified: the World Ocean; the World Ocean and all surface land waters; all surface and ground waters on the Earth; all surface and ground waters, as well as waters of the atmosphere, including atmospheric moisture; all forms of water present on the planet. Based on the concept of the phase-shell structure of the Earth, it is logically most reasonable to define the hydrosphere as a shell of the Earth, which embraces all water bodies located between the atmosphere and the lithosphere (the World Ocean, lakes, rivers, swamps, temporary and permanent snow and ice cover). The hydrosphere does not include water vapor in the atmosphere and groundwater, which are components of other geospheres, i.e. the atmosphere and the lithosphere, respectively.