The Water Cycle

Earth’s water is always moving. The water cycle describes the continuous movement of water on, above and below the surface of the earth. This cycle is made up of a few main parts: evaporation (and transpiration), condensation, precipitation, collection.

• Evaporation: Evaporation is when the sun heats up water in rivers or lakes or the ocean and turns it into vapor or steam. The water vapor or steam leaves the river, lake, or ocean and goes into the air.
  
  
• Transpiration: Transpiration is the process by which plants lose water out of their leaves. Transpiration gives evaporation a bit of a hand in getting the water vapor back into the air. Condensation: Water vapor in the air gets cold and changes back into liquid, forming clouds. This is called condensation.
  
  
• Precipitation: Precipitation occurs when so much water has condensed that the air cannot hold it anymore. The clouds get heavy and water falls back to the earth in the form of rain, hail, sleet or snow.
  
  
• Collection: When water falls back to earth as precipitation, it may fall back in the oceans, lakes, or rivers or it may end up on land. When it ends up on land, it will either soak into the earth and become part of the “ground water” that plants and animals use to drink or it may run over the soil and collect in the oceans, lakes or rivers where the cycle starts all over again.

The water cycle has no beginning or end. Water can change states among liquid, vapor and ice at various places in the cycle. These processes happen in the blink of an eye and over millions of years. Although the balance of water remains fairly constant over time, individual water molecules are constantly changing.