Water in Land, Sea, and Sky

Water covers nearly 75% of Earth. Land covers the other one-fourth of the surface.

Most of Earth’s water comes from the oceans. Ocean water is very salty. A few lakes also have salt water. The Great Salt Lake in Utah is one example. Ponds, streams, rivers, and most lakes hold fresh water. People need fresh water to live. MUCH of Earth’s fresh water is trapped in ice. Large sheets of ice are found at the North Pole and South Pole.

The movement of water from place to place and from one form to another form is called the water cycle. Condensation Precipitation Evaporation

When the sun heats liquid water, the water evaporates.

Water in its gas form is called water vapor. Tiny droplets formed by condensed water vapor form clouds.

When water vapor cools, it condenses into water droplets.

When clouds are heavy enough, water falls to the earth as precipitation. (rain, snow, sleet, hail)

Sometimes there is too much rain or too little rain, so people must do things to keep the water for times when it is needed.

In some places people build dams to help control water. This helps to store water for times when it is needed. A dam is a large wall that hold back a river. The water in the river gathers in a kind of lake called a reservoir. The reservoir stores water for people to use. In other places, people build pipes or ditches for water to travel through. These pipes are called aqueducts. The aqueducts carry water to places where it is needed.

When it rains, some water flows into streams, lakes, and rivers. Most of the rain, though, soaks into the ground. The soil and rocks underneath the ground hold water. Water held below the surface is called groundwater. We use groundwater by digging wells, which are big holes in the ground. Groundwater fills these holes.

Can we run out of fresh water? Everyone should conserve water. This means use water wisely, not wastefully. How can we conserve water?