The Water Cycle

The Water Cycle, also known as the Hydrologic Cycle, describes the continuous movement of water on, above, and below the surface of the Earth. This complex system is driven primarily by energy from the Sun and is essential for maintaining life and regulating the global Climate.

Core Processes

The cycle involves several critical phase changes. Evaporation occurs when solar energy heats the surface of the Ocean and other water bodies, converting liquid water into vapor. Additionally, Plants contribute to atmospheric moisture through a process called Transpiration. As water vapor rises into the Atmosphere, it cools and undergoes Condensation to form clouds.

When cloud particles collide and grow, they fall back to the surface as Precipitation, which includes rain, snow, and hail. According to the United States Geological Survey (USGS), the vast majority of the world's water is stored in oceans, while only a small fraction is freshwater available for human use.

Surface and Subsurface Flow

Once water reaches the land, it may flow over the surface as Runoff, eventually reaching rivers and Lakes. Alternatively, water may seep into the ground through Infiltration, where it recharges Aquifers and becomes Groundwater. This movement is vital for the health of various Ecosystems. Detailed satellite observations of these processes are provided by NASA's Global Precipitation Measurement mission.

• Climate Change
• Meteorology
• Oceanography
• Hydrogeology