Mike came running to her mom, squinched his face in disgust said, ” Eeeeeeeks, Kim is telling me that the water I’m drinking is thousands of years old. But I just took it from the tap. How can that be? She is so weird.”
Kim was Mike’s elder sister and at 10 was four years elder to him. She came running to her mum and said, ” Duh! He’s so dumb! Always complains without understanding. I was just trying to tell him that the water we all use, has been around for many years. We learnt in school today about the water cycle”
Now mum understood what Kim was trying to tell Mike – water cycle.
Did you know that water that falls from the sky once belonged to the ground, and the water that is on the ground once belonged to the sky. Earth’s has limited amount of water and the same water gets used in one form or the other. Lets learn more about it.
The water cycle is mainly controlled by the sun. It begins with evaporation. When water from the ground (present in lakes, rivers oceans or elsewhere) evaporates and mixes in the air.
Plants also contribute water to the atmosphere by the way of evaporation. A part of water that plants absorb through roots,evaporates from the leaves. It’s almost like how we first drink water and then sweat. In humans we call it perspiration. In plants, this process of evaporation through plant leaves is called transpiration.
Water vapor in the clouds cools down and becomes water again. This water is stored in clouds. This process is called condensation. Have you noticed a glass of cold water gets water droplets on the outside. That’s water vapor in the air turning back into water!
Then comes a point when clouds gets laden with as much water as it can hold. Water falls from the sky in the form of rain, snow, hail, or sleet, this process is called precipitation.
Once the water falls back on Earth it gets collected in the oceans, lakes or rivers and also on land. On land, some of it is seeps back into the Earth and gets saved as “ground water” that plants and animals can use again to drink. A large part of it goes in the oceans, lakes or rivers.
And then the cycle starts all over again!!