How come we never run out of water? After millions of years you'd think that our water supply would be all used up right! It's not though, because of one special process, the hydrologic cycle, more commonly known as "the water cycle."
This water cycle recycles the Earth's water supply. In other words, the water keeps getting reused over and over. Just think, the next glass of water you drink could have been part of a dinosaur's bath, one hundred million years ago. Water in that glass could have been a liquid, a solid, and a gas countless times over and over thanks to the water cycle.
The sun is the energy that powers this amazing process. It's energy comes in the form of light and heat. This heat causes water to EVAPORATE from oceans, rivers, lakes and even puddles. “Evaporate” means it turns the water from a liquid to a gas, or “vapor”. This vapor is then lifted by warm air currents up into the atmosphere.
When the air currents reach the cooler layers of the atmosphere, the water vapor condenses around and clings on to fine particles in the air. This step is called CONDENSATION. When enough vapor attaches itself to tiny pieces of dust, pollen or pollutants, it forms a cloud.
As the air gets more and more moist, the droplets that formed the clouds grow larger and larger. Eventually they will get so big that the swirling atmosphere can no longer hold them up. The droplets then fall from the sky as PRECIPITATION. Precipitation can be in the form of rain, snow, sleet or hail depending on other conditions.
Once the precipitation reaches the ground, several things can happen to it. First, it might be re-evaporated. Some of the precipitation will be absorbed into the ground. Once in the ground, the water can join the earth's ground water supply. This is one of the world's largest storehouses of water. The water could also be absorbed from the ground by the...