Water Cycle

Key Notes :

1. What is the Water Cycle?

  • The water cycle is the continuous movement of water within the Earth and atmosphere. It involves processes such as evaporation, condensation, and precipitation.
  • Water is constantly recycled, which is why it is a renewable resource.

2. Main Stages of the Water Cycle:

  • Evaporation:
    • This is the process where water is heated by the sun and changes from a liquid to a vapor.
    • Water evaporates from oceans, lakes, rivers, and even plants (called transpiration).
  • Condensation:
    • As water vapor rises into the air, it cools down and turns back into tiny water droplets.
    • These droplets form clouds. The process of changing from gas to liquid is called condensation.
  • Precipitation:
    • When the water droplets in the clouds become too heavy, they fall back to Earth in the form of rain, snow, hail, or sleet.
    • Precipitation occurs when the clouds can no longer hold the water vapor.
  • Runoff:
    • After precipitation, water flows over the ground, either going into rivers, lakes, or oceans.
    • This is called runoff.
  • Infiltration:
    • Some water from precipitation soaks into the ground. This process is called infiltration.
    • It replenishes groundwater, which is stored underground in aquifers.

3. The Role of the Sun:

  • The sun’s heat is the driving force behind the water cycle. It provides energy for evaporation and drives the movement of air masses, which help in cloud formation.

4. The Importance of the Water Cycle:

  • The water cycle helps in distributing freshwater across the planet.
  • It supports life by replenishing water sources like rivers and lakes.
  • The water cycle helps regulate the climate by transferring heat and moisture through the atmosphere.

5. Interdependence of Stages:

  • All stages of the water cycle are interdependent. For example, without evaporation, there would be no condensation or precipitation.

6. Human Impact on the Water Cycle:

  • Deforestation, pollution, and urbanization can affect the water cycle by reducing the amount of water that can evaporate or infiltrate into the ground.
  • Changes in the water cycle can lead to issues like flooding, droughts, or water scarcity.

7. Key Vocabulary:

  • Evaporation: The process of water turning into vapor due to heat.
  • Condensation: The change of water vapor back into liquid droplets.
  • Precipitation: Water falling from the sky in various forms like rain, snow, etc.
  • Runoff: Water flowing over land to oceans, rivers, and lakes.
  • Infiltration: The process by which water enters the soil.
  • Transpiration: The release of water vapor from plants into the air.

8. Illustration:

  • A diagram of the water cycle can help students visualize the stages and the movement of water. It shows how water moves between the atmosphere, land, and bodies of water.

Let’s practice!