The Water and Carbon Cycles

The water cycle moves H₂O between the atmosphere, land surface, oceans, and underground reservoirs through evaporation, transpiration, condensation, precipitation, runoff, and infiltration. The sun drives the cycle by evaporating water from oceans (accounting for about 86% of total evaporation). Plants contribute through transpiration—a single large oak tree can transpire over 150,000 liters of water per year. Water vapor rises, cools, condenses into clouds, and falls as precipitation. On land, water either runs off into rivers and lakes, infiltrates into soil and groundwater aquifers, or is taken up by plant roots. Groundwater can remain underground for thousands of years before eventually reaching the ocean.