WHAT IS THE WATER CYCLE?
The water cycle is the process water goes through. It is called a cycle because water continuously moves around the system. Water can be a solid, liquid or gas. Solid water is called ice. Water is a gas state is called water vapour. Liquid water is called water.
Water falls from the sky as rain. Some of this water is soaked up by the ground. The rest form puddles. As the sun heats the water in the puddles, it heats up and evaporates. That means it becomes a gas and goes into the air. The water that was soaked into the ground flows towards rivers and underground reservoirs. These underground reservoirs are where the water from wells comes from. The underground water and the water in the rivers slowly make their way to the sea. When exposed to the air and sun, the water is heated by the sun. This causes bits of the water to gain energy until they have enough energy to evaporate.
All the water vapour (evaporated water) fills the air. When the air cools, the water vapour loses energy until it becomes particles of liquid water. These particles of water form clouds in the sky. As the temperature continues to fall, more particles join the clouds. The water droplets in the clouds get bigger and bigger. When they get big enough, the water droplets begin to fall. This is the rain. The same happens to this water once it has rained. This is the water cycle and it repeats itself.
WHY IS THE WATER CYCLE IMPORTANT?
Understanding the water cycle helps us to understand why some places get more rain than others. It can also help us understand what effect our actions will have on future rainfall. Water is necessary for life, and by understanding the process water goes through, we learn how to live stably in the world.
WHAT IMPACT DOES DEFORESTATION HAVE?
Deforestation is the permanent removal of trees from an area. This involves chopping down lots of trees in an area that used to have many, until very few remain. This is done to make more land available, or to use the trees for building or fuel. Trees play an important part in the balance of the environment on earth. They provide a place for many animals to live. They also play a large role in the water cycle and the carbon cycle (see book on the carbon cycle).
Trees in large forests attract water vapour and produce more water vapour than areas without trees. This results in air with more water in. Forests are also often cooler, due to the shade. This mean the air cools further. This means that areas with more trees also have more rain. This means that deforestation can decrease the rainfall in an area. So, it is a good idea to look after the forests so you can have a good amount of rain.
Trees also absorb the gas carbon dioxide. This gas contributes to the greenhouse effect, which traps heat in the air, making the climate change. Too much carbon dioxide can cause extreme weather and large periods of drought. This means trees can help keep the climate in a good state. But, cutting down trees can be an important part of economic life. It is important to keep the ability to trade and process natural resources. So, it is important to understand how to sustainably use the forests. That is, how to balance the use of the forest, with the need to maintain the forest. One way of doing this is to make sure to replant the forests at the same rate they are chopped down.