What is the Water Cycle?
The water cycle, also known as the hydrologic cycle, is the continuous process by which water circulates through Earth's atmosphere, land, and oceans. It involves key stages: evaporation, where water turns into vapor from surfaces like oceans and lakes; condensation, forming clouds; precipitation, as rain, snow, or hail; runoff, flowing into rivers and oceans; and infiltration, replenishing groundwater. This natural loop maintains Earth's water balance and supports life.
Key Components of the Water Cycle
Core components include evaporation driven by solar energy, transpiration from plants adding moisture to the air, and the role of gravity in runoff and percolation. These processes are interconnected; for instance, warmer temperatures accelerate evaporation, increasing atmospheric moisture. The cycle's efficiency relies on balanced energy inputs, but human activities and global warming are shifting these dynamics.
Practical Example: Regional Water Flow
Consider a forested watershed: Rain (precipitation) falls, some infiltrates soil to recharge aquifers, while excess runs off into streams. In a balanced cycle, this sustains river levels year-round. However, in California's Sierra Nevada, reduced snowpack due to warmer winters leads to earlier melt and summer droughts, disrupting water supply for agriculture and cities like Los Angeles.
Disruptions from Climate Change and Their Importance
Climate change intensifies the water cycle by raising global temperatures, causing more evaporation and extreme weather. This results in heavier downpours and floods in some areas, while others face prolonged droughts. Sea levels rise from melting ice, salinizing coastal aquifers. These disruptions threaten food security, biodiversity, and water resources for billions, underscoring the need for mitigation like reducing emissions to stabilize the cycle.