How does the Earth change over time? How long would it take my yard or neighborhood to become unrecognizably different? The answers to these questions depend upon your climate, the shape of the land, where you are on Earth, and even how humans behave! In this book you will learn about how natural forces, especially the force of water, can build up and wear down the land.
THE WATER CYCLE
The water cycle, or hydrologic cycle as geologists call it, is the never-ending transformation of water from solid to liquid to gas, and its continual travels from place to place. Two parts of the water cycle are commonly misunderstood. Evaporation means the change of any liquid to a gas. In the water cycle his happens not only to the ocean but to any other exposed water, even beads of sweat on skin! The sun provides the energy for this part of the cycle. Evaporated water is invisible and is called water vapor. Condensation is another difficult term. Condensation means the change of a gas to a liquid. When water vapor changes to liquid, it is condensing. The tiny droplets that form from condensation make up clouds. They are so small that they can be moved by air, but they are big enough to see. If they grow large enough in the cloud, it will rain, sleet or snow.
After precipitation reaches the ground, it may evaporate again or go through other parts of the cycle, such as becoming groundwater, entering the ocean, or going through a tree or other organism. The part of the water cycle where water runs across the ground is when water may have a huge effect on Earth's appearance and people.
