The water cycle
Click on image for full size
Copyright University Corporation for Atmospheric Research
Earth's Water Cycle
Once upon a time, the rain falling today was in the ocean. At other times it was snow that covered a high mountaintop.
Water is always moving around the planet. Water can be in the atmosphere, on the land, in the ocean, and even underground. It is recycled over and over through the water cycle. In the cycle, water changes state between liquid water, ice, and water vapor.
Water that is at the top of the ocean, rivers, and lakes turns into water vapor in the atmosphere by the process of evaporation. Water vapor can also form from snow and ice. It can also evaporate from plants.
The water vapor rises in the atmosphere and cools. The cooler temperature turns the water vapor into tiny water droplets by a process called condensation. Those water droplets make up clouds. The water droplets grow larger when they combine with each other. In time, they become too heavy to stay in the air. Then they fall to the ground as rain, snow and other types of precipitation.
Most of the precipitation that falls becomes a part of the ocean or part of rivers, lakes, and streams that lead to the ocean. Some of the snow and ice that falls as precipitation stays at the Earth surface in glaciers and other types of ice. Some of the precipitation seeps into the ground and becomes a part of the groundwater.
Shop Windows to the Universe Science Store!
The Summer 2010 issue of The Earth Scientist
, available in our online store
, includes articles on rivers and snow, classroom planetariums, satellites and oceanography, hands-on astronomy, and global warming.
You might also be interested in:
Rivers are very important to Earth because they are major forces that shape the landscape. Also, they provide transportation and water for drinking, washing and farming. Rivers can flow on land or underground...more
Have you ever left a glass of water out for a long time? Did you notice that the water disappears after a few days? That's because it evaporated! Evaporation is when water passes from a liquid to a gas....more
Frozen water is found in many different places on Earth. Snow blankets the ground at mid and high latitudes during winter. Sea ice and icebergs float in the chilly waters of polar oceans. Ice shelves are...more
Condensation is when water changes its state from a vapor or gas to a liquid. Condensation is responsible for the formation of clouds. Common examples of condensation are: dew forming on grass in the early...more
Raindrops form when tiny water droplets collide together in clouds to form bigger ones. When they get too heavy, rain falls out of the clouds. Rain is more than 5mm in diameter. The types of clouds that...more
The deep ocean waters are under pressure and are much colder than layers of the ocean which are closer to the surface. Dissolved carbon dioxide seems to be absent from the deep ocean water and as a result...more
An aquifer is the name for a layer of rock which is capable of holding a large amount of water. Some layers are better at holding water than others, for example a layer of sandstone can hold a good deal...more