1. Evaporation: The sun's energy heats the surface water in oceans, lakes, rivers, and even the soil, transforming it into water vapor and lifting it into the atmosphere.
2. Condensation: As the water vapor rises and cools, it changes back into liquid water droplets, forming clouds.
3. Precipitation: When the droplets in clouds become too heavy, they fall back to Earth as rain, snow, sleet, or hail.
4. Runoff: Precipitation that falls on land flows over the surface, collecting in rivers, streams, lakes, and oceans.
5. Infiltration: A portion of the precipitation soaks into the ground, replenishing groundwater reserves.
6. Transpiration: Plants absorb water from the ground and release it into the atmosphere through their leaves, contributing to the cycle.
Purification: Throughout the cycle, water undergoes natural purification processes:
* Evaporation: Only pure water vapor rises, leaving behind salts and impurities.
* Condensation: As water vapor condenses, it forms clean droplets.
* Filtration: As water flows through the ground, it's filtered through layers of soil and rock, removing impurities.
Key sources of clean freshwater:
* Groundwater: Water stored in underground aquifers, often filtered through layers of rock and soil.
* Surface water: Water found in rivers, lakes, and streams, which is usually replenished by precipitation and runoff.
* Snowmelt: Water released from melting snow and ice, which is often very pure.
It's important to note:
* While the hydrologic cycle naturally purifies water, human activities can contaminate it with pollutants.
* Freshwater resources are finite and vulnerable to depletion, making conservation crucial.
Understanding the hydrologic cycle helps us appreciate the vital role of water in nature and the importance of protecting it.