Water Cycle Diagram: Interactive 2D and 3D

What is the water cycle?

The water cycle is the never-ending trip that water takes around our planet. NOAA describes it as the continuous movement of water within the Earth and atmosphere. The water in a puddle today might be a cloud next week, snow on a mountain next winter and part of an ocean wave after that.

Two things keep it moving. Energy from the Sun warms water so it rises into the air as vapor. Gravity pulls rain and snow back down and makes rivers and groundwater flow downhill to the sea. Earth isn't making new water or losing it to space; it keeps recycling the same supply.

Scientists talk about the water cycle in two kinds of pieces:

• Stores (also called pools or reservoirs) are places where water stays for a while: oceans, ice caps and glaciers, lakes, rivers, the soil, the air and groundwater.
• Processes (also called fluxes) move water from one store to another: evaporation, transpiration, sublimation, condensation, precipitation, runoff, infiltration and groundwater flow.

The diagram above shows all of them. Tap any numbered pin to read what it means, then try the label and order quizzes.

Water cycle steps in order

Most water cycle diagrams for kids start at the ocean, because that is where most water is. Here is one drop's trip, the same path as the Order it quiz:

1. Evaporation. The Sun heats the ocean, and some water turns into an invisible gas, water vapor, which rises with warm air.
2. Condensation. Higher up, the air is colder. The vapor cools and turns back into tiny liquid drops around specks of dust and salt. Billions of drops make a cloud.
3. Precipitation. Drops bump into each other and grow until they are too heavy to float. They fall as rain, snow, sleet or hail. Wind often carries the cloud over land first.
4. Runoff. Rain that doesn't soak in flows downhill into streams and rivers.
5. Collection. Rivers carry the water to lakes and back to the ocean, where the Sun can evaporate it again.

That is the short loop. Real water takes plenty of detours, which is why the full diagram has nine processes instead of four.

The nine processes in the water cycle diagram

Evaporation: how water gets into the air

Evaporation is the biggest way water enters the air. According to the USGS, about 90 percent of the moisture in the atmosphere evaporated from oceans, seas, lakes and rivers. Plants supply most of the rest, and a very small amount comes from sublimation.

The ocean does most of the work because it covers more than 70 percent of Earth's surface. When seawater evaporates, the salt stays behind, so the vapor and the rain it becomes are fresh water. That's how the water cycle turns salty ocean into fresh rain for the land.

You can see evaporation at home: wet clothes on a line dry faster on a hot, sunny, windy day. Heat and moving air both speed it up.

Transpiration: plants breathe out water

Plants drink water through their roots and lift it up to their leaves. Tiny openings on the leaves, called stomata, let water vapor escape into the air. That is transpiration. Scientists often lump it together with evaporation from the soil and call the pair evapotranspiration.

It adds up to a lot of water. The USGS estimates that an acre of corn gives off about 3,000 to 4,000 gallons of water a day, and a large oak tree can transpire 40,000 gallons in a year. Try it: tie a clear plastic bag around a leafy branch on a sunny morning. Within an hour or so, drops of water collect inside the bag.

Condensation: how clouds form

Air gets colder the higher you go. When warm, damp air rises and cools, it can't hold as much water vapor, and the extra vapor turns back into liquid drops. NOAA explains it this way: condensation happens when there is more water vapor than the air can hold at its current temperature.

The vapor needs something to cling to, so it condenses on specks of dust, smoke and sea salt. Each cloud drop is tiny, but there are so many of them that we see a cloud. Condensation is also why a cold glass of lemonade "sweats" on a summer day, and why your breath makes a little cloud on a winter morning.

Precipitation: rain, snow, sleet and hail

Cloud drops bump together and merge. When they get too heavy for rising air to hold up, they fall as precipitation. If the air is cold enough, the water falls as snow; sleet and hail form when drops freeze on the way down or are tossed up and down inside storm clouds.

Wind moves clouds a long way, which matters: NASA's precipitation scientists point out that the movement of water into and out of the atmosphere shapes Earth's weather. The USGS notes that over the oceans more water evaporates than falls as rain, while over land more falls than evaporates. That difference is the water that flows back to the sea in rivers and underground.

Runoff, infiltration and groundwater

When rain or melting snow reaches the ground, it can go two ways.

• Runoff flows over the surface into streams and rivers. Steep hills, soaked or frozen ground, and pavement all make more runoff. Spring snowmelt sends a big pulse of runoff down mountain rivers.
• Infiltration soaks the water into the soil, like a sponge. Plant roots use some. The rest can keep trickling deeper, which NOAA calls percolation, until it reaches a zone where every space between grains of sand and rock is full of water.

The top of that full zone is the water table, the dashed line in the diagram. The water below it is groundwater, and a layer of rock or sand that holds a lot of it is an aquifer. Groundwater moves slowly downhill and seeps into rivers, lakes, springs and the ocean. That is why many streams keep flowing even when it hasn't rained for weeks. Groundwater can stay underground for a long time; NOAA notes that some sources take a long time to refill once they are pumped out.

Where is Earth's water?

The bar under the diagram shows the USGS estimate of where all of Earth's water is. The ocean holds almost all of it.

Only about 2.5 percent of Earth's water is fresh, and most of that is locked in ice or hidden underground. The USGS says the fresh water in all the world's rivers and lakes is about 22,300 cubic miles, about 1/150th of one percent of the total. That small slice is what most people, plants and animals rely on every day, which is a good reason to keep it clean.

How long does water stay in each part of the cycle?

It varies a lot. The USGS says a water molecule that evaporates spends about 10 days in the air before falling again. Water might stay in a river for days or weeks, in a big lake for years, and in deep groundwater or an Antarctic ice sheet for thousands of years. The water cycle never stops, but some of its trips are very slow.

Is the water cycle changing?

Yes. NOAA explains that warmer air causes more evaporation and can hold more water vapor. That can mean longer gaps between rains and heavier downpours when it does rain. Water vapor also traps heat, which adds more warming. People change the cycle directly too, by building dams, moving rivers, pumping groundwater and covering land with pavement that turns rain into runoff.

How to draw the water cycle

A water cycle drawing is a classic science notebook page. Here is a simple plan that matches our diagram:

1. Draw a wavy ocean on the left, land rising to a mountain on the right, and a sun in the top corner.
2. Add a cloud over the ocean and a second cloud over the mountain.
3. Draw wavy arrows going up from the ocean to the first cloud and label them evaporation. Write condensation by the cloud.
4. Draw rain falling from the second cloud and label it precipitation.
5. Draw a river from the mountain back to the ocean and label it runoff. Label the ocean collection.
6. For extra credit, add trees with arrows going up (transpiration) and arrows going down into the ground (infiltration).

Then compare it with the labeled water cycle diagram printable, or test yourself with the water cycle worksheet and its word bank.

Explore the water cycle in 3D

Select Open in 3D to see the same nine parts in a low-poly landscape: a sunny ocean, a forest, a winding river, snowy mountains and two clouds, with the ground cut away so you can see the soil and the groundwater below the water table. Vapor drifts up from the sea, the trees and the snow; rain falls on the mountains; water runs down the river and seeps underground. Tap any part for its explanation, take the guided tour, or choose Follow a drop to watch one drop travel the whole loop. If your device can't show 3D graphics, the page falls back to the 2D explorer.

Water cycle activities for kids

• Water cycle in a bag. Draw a sun and a cloud on a zip-top bag, add a few spoonfuls of water (a drop of blue food coloring helps), seal it and tape it to a sunny window. Over a day you'll see condensation on the top of the bag and "rain" running down the sides.
• Paper craft. NOAA's JetStream weather school has a free water cycle paper craft that folds into a 3D model in about 40 minutes.
• Be a water molecule. Set up stations around the house (ocean, cloud, glacier, river, groundwater) and roll a die to decide where to go next. It shows that water doesn't move in one neat circle.
• Label it twice. Do the Label it quiz here, then print the numbered water cycle diagram and fill it in from memory.

The water cycle connects to the rock cycle, since rain and rivers weather and erode rock, and to the states of matter, since every step is water changing between solid, liquid and gas. If you want a full course that builds on it, compare the options in our best homeschool science curriculum guide or browse science programs, many of which families can pay for with a state scholarship or education savings account.