Water Science School
Water Cycle Components
Earth's water is always in motion, and the natural water cycle, also known as the hydrologic cycle, describes the continuous movement of water on, above, and below the surface of the Earth. Water is always changing states between liquid, vapor, and ice, with these processes happening in the blink of an eye and over millions of years.
The Water Cycle for Schools and Kids
Use our Water Cycle for Schools area to introduce water-cycle science to elementary and middle-school students.
ExploreThe Water Cycle for Adults and Advanced Students
We offer extensive analyses about all of the parts of the water cycle; this area is recommended for high-school students to adult ages.
Explore
The Water Cycle
The U.S. Geological Survey (USGS) offers you the most comprehensive information about the natural water cycle anywhere. We've developed Web pages aimed at both younger students and kids and at ...
The Water Cycle for Schools and Kids
Earth's water is always in movement, and the natural water cycle, also known as the hydrologic cycle, describes the continuous movement of water on, above, and below the surface of the Earth. Water is always changing states between liquid, vapor, and ice, with these processes happening in the blink of an eye and over millions of years.
Note: This section of the Water Science School...
The Water Science School -- What We Offer
The U.S. Geological Survey's Water Science School
Where anyone of any age can learn all about water.
The Fundamentals of the Water Cycle
Earth's water is always in movement, and the natural water cycle, also known as the hydrologic cycle, describes the continuous movement of water on, above, and below the surface of the Earth. Water is always changing states between liquid, vapor, and ice, with these processes happening in the blink of an eye and over millions of years.
How Much Does a Cloud Weigh?
I don't know anyone who is afraid to walk underneath a cumulus cloud because they are afraid it might fall on them. We don't think of clouds even having weight because they are floating. But, clouds are made up of a physical substance, water, and water is quite heavy, so clouds must have weight. We will explain this "paradox" to you if you read on.
Rain and Precipitation
Rain and snow are key elements in the Earth's water cycle, which is vital to all life on Earth. Rainfall is the main way that the water in the skies comes down to Earth, where it fills our lakes and rivers, recharges the underground aquifers, and provides drinks to plants and animals.
Water Science Photo Galleries
Learn about water using pictures
Streamflow and the Water Cycle
What is streamflow? How do streams get their water? To learn about streamflow and its role in the water cycle, continue reading.
Note: This section of the Water Science School discusses the Earth's "natural" water cycle without human interference.
Snowmelt Runoff and the Water Cycle
Perhaps you've never seen snow. Or, perhaps you built a snowman this very afternoon and perhaps you saw your snowman begin to melt. Regardless of your experience with snow and associated snowmelt, runoff from snowmelt is a major component of the global movement of water, possibly even if you live where it never snows.
Note: This section of the Water Science School discusses the...
Evaporation and the Water Cycle
For the water cycle to work, water has to get from the Earth's surface back up into the skies so it can rain back down and ruin your parade or water your crops or yard. It is the invisible process of evaporation that changes liquid and frozen water into water-vapor gas, which then floats up into the skies to become clouds.
Note: This section of the Water Science School discusses the...
Condensation and the Water Cycle
The air is full of water, as water vapor, even if you can't see it. Condensation is the process of water vapor turning back into liquid water, with the best example being those big, fluffy clouds floating over your head. And when the water droplets in clouds combine, they become heavy enough to form raindrops to rain down onto your head.
Note: This section of the Water Science...
Precipitation and the Water Cycle
The air is full of water, even if you can't see it. Higher in the sky where it is colder than at the land surface, invisible water vapor condenses into tiny liquid water droplets—clouds. When the cloud droplets combine to form heavier cloud drops which can no longer "float" in the surrounding air, it can start to rain, snow, and hail... all forms of precipitation, the superhighway moving water...
The Atmosphere and the Water Cycle
The atmosphere is the superhighway in the sky that moves water everywhere over the Earth. Water at the Earth's surface evaporates into water vapor which rises up into the sky to become part of a cloud which will float off with the winds, eventually releasing water back to Earth as precipitation.
Note: This section of the Water Science School discusses the Earth's "natural" water...