Introduction

Did you know that water changes phase constantly on our planet?

Phase changes allow water in the Earth’s hydrosphere to cycle continuously.

Only 3 percent of the water in Earth’s hydrosphere is freshwater. Of that 3

percent, merely 0.1 percent is accessible for use. The majority of the freshwater

in Earth’s hydrosphere is frozen as snow or glaciers. 97 percent of the water in our hydrosphere exists as salt water in Earth’s vast seas and oceans.

When the sun heats the liquid water on Earth, its added energy provides the heat needed for evaporation to occur. During evaporation, liquid water becomes water vapor, which is a gas.

Locations in humid climates, like South Florida’s Everglades National Park, have a lot of water vapor in the atmosphere. The plants and animals here are adapted to life in warm, moist air.

When water vapor in the air begins to cool, the molecules slow down and condense. This is how clouds are formed.

Clouds are made of tiny water droplets and ice crystals with a density so low that they float in the air.

As the water droplets that compose clouds become larger, their density increases, causing them to fall to the ground. This is called precipitation. But precipitation is not only rain.

It also includes snow, sleet and hail.

Whether precipitation collects in rivers and streams, flowing by the gravitational pull of Earth, or soaks into ground, it eventually arrives back into lakes and ocean basins. This process is called collection.

It is in these vast bodies of water that the warmth of our sun heats water molecules, once again, to evaporate and enter back into the continuous cycle of water with our hydrosphere.