Earth’s Water

Earth’s Water

2.2 identify and locate major land masses and bodies of water

• The Caspian Sea in southeastern Europe/southwestern Asia is actually a salt lake–the largest one on Earth. It is a lake, not a sea, because it is surrounded by land. The ancient Romans called the Caspian a sea because its water was salty. Australia’s Lake Eyre, Venezuela’s Lake Maracaibo, and Utah’s Great Salt Lake are other notable saltwater lakes

The Water Cycle

• The part of the earth that is covered by water is called the hydrosphere.

• Most of the hydrosphere is salt water, found in the oceans, seas, and some lakes.

• The rest of the hydrosphere is the freshwater of lakes, rivers, and springs.

• The sun’s heat evaporates water, which remains in the air until the air cools.

• The cool air returns the water to Earth in the form of rain, snow, or sleet.

• The total volume of the hydrosphere remains relatively constant because the evaporated water returns to Earth as precipitation.

Bodies of Salt Water Oceans

• About 97 percent of the hydrosphere is a huge body of

salt water divided into four oceans: the Atlantic, the

Pacific, the Indian, and the Arctic Oceans.

Seas, Gulfs, and Bays

• Large bodies of salt water partially enclosed by land comprise seas, gulfs, and bays.

Ocean Water to Drinking Water

• Because of the great demand for drinking water, people are experimenting with desalination–the removal of salt from ocean water.

2.4 explain the significance of water as a renewable resource

Bodies of Freshwater

• Only about 3 percent of the hydrosphere is freshwater, and most of it is frozen in glaciers and icecaps, inaccessible to people.

Lakes, Streams, and Rivers

• A lake is a body of freshwater completely surrounded by land. Only a few lakes are made of salt water.

• Streams are narrow bodies of water flowing through areas of land. Rivers are large streams that carry greater volumes of water.

• Because rivers and streams flow through land, they carry freshwater to people and animals.

• Most people and animals live near sources of freshwater.

Groundwater

• Ground water is freshwater lying beneath the planet’s surface.

• Natural springs and handmade wells allow people to retrieve groundwater.