The continuous exchange of water between the earth and the atmosphere is called what?

• A. Reverse osmosis
• B. Evapotranspiration
• C. Hydrologic cycle
• D. Cycle of infiltration

Answer: (C)

The continuous exchange of water between the earth and the atmosphere is described by the hydrologic cycle. This cycle encompasses every step that moves and stores water: evaporation from oceans and other bodies, transpiration and evaporation from land surfaces (together called evapotranspiration), condensation into clouds, precipitation back to the surface, and processes like infiltration into soil and groundwater, as well as runoff and storage in lakes and rivers. Evapotranspiration is a part of the cycle, not the whole thing, and infiltration is one specific step within the cycle. Reverse osmosis is a laboratory or engineering process for separating water from salts, not the natural cycle. So the term that names the entire, interconnected system is the hydrologic cycle.