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Back to the water cycle on the USGS Water Science School.

Fog

Fog is just a cloud that happens to be hanging around on the Earth's surface.

Fog contains very tiny liquid water particles, like a cloud, and floats, like a cloud. Actually, fog IS a cloud, but one that swirls around your feet instead of high in the sky. Fog forms when air containing invisible water vapor encounters cooler temperatures (here, next to the ground) and the water vapor condenses out into liquid water-the cloud.

In this picture, as the day warms the air next to the ground will warm, too, and the fog particles will again evaporate back into invisible water vapor.

Groundwater flow

If you pour a glass of water onto the ground it usually sinks right in ( infiltration), so you can imagine how much water sinks into the ground during a major storm ( Find out here). Here in Atlanta, Ga, USA it rains about 50 inches/year. Over a 100 square mile (10 miles by 10 miles) area that means 87,000 billion gallons of water falls, with much of it soaking into the ground to recharge groundwater.

Yes, water below your feet is moving all the time, but, no, if you have heard there are rivers flowing below ground, that is not true.

Groundwater flow. Relate to recharge a battery.

Groundwater

When you are standing on the ground, you're not only standing on dirt, but on water-a lot of water. The dirt and rock below your feet contains lots of spaces and cracks, and water can exist in these open spaces. In fact, over 20 times the amount of water in all of Earth's rivers and lakes is in the ground.

When you pour a glass of water on your yard, the water sinks (infiltrates) into the ground and gets back into being a vital part of the global water cycle.

Of course, the rock underground is different all over the world, so how much and where water occurs of water underground is different everywhere. Deep in the ground, the rock becomes very hard and solid (no open spaces to hold water), and it also gets very hot, so no liquid water is found deep in the Earth.

Ice and snow

Ice and glaciers are part of the water cycle, even though the water moving in them changes very slowly. The amount of ice on the Earth goes up and down as the world's climate cools and warms over thousands of years.

Lucky for us we're now in a warmer phase of the Earth's history, but the last Ice Age was only 18,000 years ago. At that time, ice covered the northern part of North America.

Ice and glaciers are still around today, as this picture shows. In fact, most of the world's freshwater, about 68 percent, is locked up in ice, snow, and glaciers.

Oceans

If you look at this picture (or click on it for a larger version) you see that "tiny" blue ball sitting in the middle of the United States-if all the water on, in, and above the Earth was collected in one big ball, this is the size it would be.

The oceans are, by far, the largest reservoir of water on earth-over 96% of all of Earth's water exists in the oceans.

Oceans are important to the water cycle because almost all the water that evaporates from liquid to water vapor (which forms clouds) comes from the oceans.

Precipitation

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, it can start to rain, snow, hail....all forms of precipitation.

The amount of precipitation that falls is different all around the world. In deserts, such as in Chile, it may only rain one inch per year, while on some mountains in Hawaii and in India, it can rain more than 600 inches per year. That is almost 2 inches every day!

Precipitation is the "exit ramp" back to earth from the water-cycle superhighway in the sky that is moving clouds all around the globe.

Rivers

Most of the rain that falls stays on the land surface and, due to gravity, starts running downhill. This runoff water will accumulate in creeks ... I mean, in streams ...no, I mean, in rivers. Actually, no matter what you call them, rivers are responsible for moving a lot of water off of the land and back into oceans.

Of course, plants, animals, and people interact with rivers, as all kinds of life seems to thrive around rivers. If you look at a map of the world, you see how people naturally build their cities next to rivers.

And, as this satellite picture of the Nile River in Egypt, you can often pick out the rivers because of the green growth growing along them.

Seepage

You know all about seepage. When you spill your red fruit drink onto your Mom's white carpet, she rushes (after glaring at you) to get a sponge to soak up the liquid before it "seeps down into the carpet".

With the water cycle, seepage occurs when precipitation falls on the landscape and starts to soak into the ground. The "Why?" this happens is simply gravity. But, seepage doesn't just happen downward! Water seeps upwards and sideways, too, from the ground into the bottom of rivers, lakes, and the oceans. Some of the water you see flowing in a river has come up from the ground.

The Sun

Who's the Boss? The sun is the real boss of the water cycle, and it doesn't even live here on Earth. The sun is what makes the water cycle work. The sun provides what almost everything on Earth needs to go-energy, or heat.

The sun's heat allows liquid water to evaporate into water vapor, which in the main way water gets from the land surface back into the sky.

The sun also participates in moving water around the Earth by being the reason winds exist. The winds move clouds and the weather all over the place; all of this mixing up and moving is an important part of the water cycle.

Evapotranspiration (Evaporation and transpiration)

When a person breathes, their breath contains water molecules. All the plants around you are "breathing" and releasing water, too. The term is called "transpiration", and although a brussels sprout doesn't have a mouth, it has tiny holes in its leaves that allow water to leave the leaf, via evaporation, and go into the air.

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Interactive Water Cycle Diagram for Kids (Intermediate)

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The Water Cycle for Kids, from the USGS Water Science School.

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This article will read aloud to you :)

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Pour a glass of and take a sip. Pretty good, isn't it? Would you believe the you're drinking has been around for millions of years? It's true!

Before any creatures were living on land, your was part of the . The we have on Earth has been here for a very, very long time, and Mother has been constantly recycling it through the .

Once is in the , it rises into the atmosphere , cools, and forms clouds through a process called condensation . If you have ever poured a cool glass of lemonade on a hot day, you have probably seen condensation in action.

The next step in the - precipitation - occurs when so much has condensed that the can no longer hold it. Clouds become heavier and heavier until eventually the falls back to the Earth in the form of precipitation . Depending on atmospheric conditions and temperatures, precipitation can arrive on Earth as , hail, sleet, freezing , or snow.

When falls back to Earth as precipitation , it ends up in rivers, lakes, oceans, swimming pools, barrels, bird baths, and lots of other places. This final step of the is called collection .

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Pour a glass of and take a sip. Pretty good, isn't it? Would you believe the you're drinking has been around for millions of years? It's true! Before any creatures were living on land, your was part of the .