The Short Answer:
The water cycle is the path that all water follows as it moves around Earth in different states. Liquid water is found in oceans, rivers, lakes—and even underground. Solid ice is found in glaciers, snow, and at the North and South Poles. Water vapor—a gas—is found in Earth’s atmosphere.
Water can be found all over Earth in the ocean, on land and in the atmosphere. The water cycle is the path that all water follows as it moves around our planet.
Credit: NASA/JPL-Caltech Data source: NASA's Earth Observatory
On Earth, you can find water in all three states of matter: solid, liquid and gas. Liquid water is found in Earth’s oceans, rivers, lakes, streams—and even in the soil and underground. Solid ice is found in glaciers, snow, and at the North and South Poles. Water vapor—a gas—is found in Earth’s atmosphere.
How does water travel from a glacier to the ocean to a cloud? That’s where the water cycle comes in.
The Water Cycle
Credit: NASA/JPL-Caltech
The Sun’s heat causes glaciers and snow to melt into liquid water. This water goes into oceans, lakes and streams. Water from melting snow and ice also goes into the soil. There, it supplies water for plants and the groundwater that we drink.
Snow falling on a glacier during winter months usually replaces any water that melts away in the summer. However, due to Earth’s overall warming, most glaciers today are losing more ice than they regain, causing them to shrink over time.
How does water get into the atmosphere? There are two main ways this happens:
- Heat from the Sun causes water to evaporate from oceans, lakes and streams. Evaporation occurs when liquid water on Earth’s surface turns into water vapor in our atmosphere.
- Water from plants and trees also enters the atmosphere. This is called transpiration.
Warm water vapor rises up through Earth’s atmosphere. As the water vapor rises higher and higher, the cool air of the atmosphere causes the water vapor to turn back into liquid water, creating clouds. This process is called condensation.
When a cloud becomes full of liquid water, it falls from the sky as rain or snow—also known as precipitation. Rain and snow then fill lakes and streams, and the process starts all over again.
Clouds, like these over the savannah in Nairobi, Kenya, form when water vapor in the atmosphere condenses back into liquid water. Credit: Department of State
Why Do We Care About the Water Cycle?
We care about the water cycle because water is necessary for all living things. NASA satellites orbiting Earth right now are helping us to understand what is happening with water on our planet.
Water in the Soil
Humans need water to drink, and to water the plants that grow our food. NASA has a satellite called SMAP—short for Soil Moisture Active Passive—that measures how much water is in the top 2 inches (5 cm) of Earth’s soil. This can help us understand the relationship between water in the soil and severe weather conditions, such as droughts.
Water in the Atmosphere
NASA’s CloudSat mission studies water in our atmosphere in the form of clouds. CloudSat gathers information about clouds and how they play a role in Earth’s climate. Also, the international satellite called the Global Precipitation Measurement Mission (GPM) observes when, where and how much it rains and snows on Earth.
Water in the Oceans
As Earth’s climate becomes warmer, land ice at the North and South Poles starts melting. The water then flows into the ocean, causing sea level to rise. NASA’s Jason-3 mission—short for Joint Altimetry Satellite Oceanography Network-3—orbits Earth collecting information about sea level and ocean temperature. This helps track how the ocean responds to Earth’s changing climate.
NASA is also tracking how Earth’s water moves all around our planet. This is the work of the GRACE-FO—or Gravity Recovery and Climate Experiment-Follow On—mission. It tracks the movement of water from one month to the next, and can even measure changes in deep groundwater hundreds of feet below Earth’s surface.
NASA’s Aqua satellite also collects a large amount of information about Earth’s water cycle, including water in the oceans, clouds, sea ice, land ice and snow cover.
Related NASA Missions
Aqua CloudSat GPM GRACE-FO Jason-3 SMAP
FAQs
The water cycle shows the continuous movement of water within the Earth and atmosphere. It is a complex system that includes many different processes. Liquid water evaporates into water vapor, condenses to form clouds, and precipitates back to earth in the form of rain and snow.
What are the water cycle 4 stages? ›
There are four main parts to the water cycle: Evaporation, Convection, Precipitation and Collection. Evaporation is when the sun heats up water in rivers or lakes or the ocean and turns it into vapour or steam.
What is a water cycle for kids? ›
The Short Answer: The water cycle is the path that all water follows as it moves around Earth in different states. Liquid water is found in oceans, rivers, lakes—and even underground. Solid ice is found in glaciers, snow, and at the North and South Poles. Water vapor—a gas—is found in Earth's atmosphere.
Why is the water cycle? ›
The water cycle is an extremely important process because it enables the availability of water for all living organisms and regulates weather patterns on our planet. If water didn't naturally recycle itself, we would run out of clean water, which is essential to life.
What best defines the water cycle? ›
The water cycle describes how water evaporates from the surface of the earth, rises into the atmosphere, cools and condenses into rain or snow in clouds, and falls again to the surface as precipitation.
What are the 5 processes of the water cycle? ›
Of the many processes involved in the water cycle, the most important are evaporation, transpiration, condensation, precipitation, and runoff. Although the total amount of water within the cycle remains essentially constant, its distribution among the various processes is continually changing.
What is the water cycle for Grade 7? ›
Water of Class 7
The water from the oceans and surface of the earth evaporates and rises up in the air. It cools and condenses to form clouds and then falls back to the earth as rain, snow or hail. This circulation of water between the oceans and land is called water cycle.
What is water cycle grade 5? ›
In the water cycle, water from lakes, rivers, and oceans evaporate and enter the atmosphere where it cools, condenses into liquid water, and comes back to Earth as rain.
What is water cycle for 6? ›
The water cycle is a process, in which water evaporates from the surface into the atmosphere, cools and condenses through the rain in clouds and again falls on the surface with the process of precipitation.
What is the water cycle answer? ›
The water cycle depicts the continual flow of water on Earth and in the atmosphere. It's a complicated system with many separate processes. Liquid water evaporates into water vapour, condenses into clouds, and precipitates as rain and snow on the ground.
What are the major 4 steps in the water cycle? The major 4 steps are evaporation of water, then condensation, precipitation and collection. The sun evaporates water sources and contributes to the formation of water vapor. These water vapour accumulate in the atmosphere as clouds.
What powers the water cycle? ›
The Sun provides the energy to power the water cycle. When water changes state in the water cycle, the total number of water particles remains the same. The changes of state include melting, sublimation, evaporation, freezing, condensation, and deposition.
What is the water cycle for 6th grade? ›
Water evaporates from the surface of Earth, rises into the atmosphere, cools and condenses, and falls again to the surface as precipitation. The water falling on land moves along the surface in rivers and streams and collects in bodies of water such as lakes and oceans.
What is the water cycle explained in 5 steps? ›
water cycle, cycle that involves the continuous circulation of water in the Earth-atmosphere system. Of the many processes involved in the water cycle, the most important are evaporation, transpiration, condensation, precipitation, and runoff.
What is water cycle 10 line? ›
The water cycle includes the alternate of energy, which leads to temperature modifications. When water evaporates, it takes up strength from its environment and cools the environment. When it condenses, it releases power and warms the environment. These warmness exchanges have an impact on weather.
