Learning About the Water Cycle
Water is constantly on the move through the ocean, land, in the atmosphere, and underground, and is essential for life on earth. It is recycled over and over through a process known as the water cycle. During this cycle, water changes state between solids (ice), liquids (water), and gases (water vapor). The rain that you see falling from the sky could have been water in the ocean only days beforehand.
In the atmosphere, water vapor rises and cools which forms water droplets through a process known as condensation. Condensation is the process in which water changes from its state of a gas or vapor into a liquid. These tiny water droplets combine to form clouds. Once the droplets become too heavy to stay in the air, they begin to fall to the ground in the form of rain, snow, or other forms of precipitation. A large majority of the precipitation that falls become a part of an ocean, river, lake, or stream. Snow and ice that falls to Earth may lay on its surface within glaciers or other forms of ice. Some precipitation seeps into the ground to become groundwater. The length of time in which water spends in each phase of the water cycle varies. A drop of water may spend several thousand years in the ocean before transferring to the next phase of the water cycle, while a drop of water spends an average of eight days in the atmosphere before falling to Earth.
Water's state, whether it be a solid, liquid, or gas, is generally determined by temperature. Water continuously changes states, but the amount of water on Earth remains the same.
Water is an important part of life on this planet, covering more than three-fourths of the Earth's surface. Learn more about the water cycle that provides us with water to drink, food to eat, and sufficient weather patterns required to successfully grow crops.