How Does Water Transform?

Water can change into three different forms.

Water exists in three different forms, or states: solid, liquid, and gas. The water cycle is the movement of water from one state to another. Water in its solid state is ice. As ice absorbs heat, it will eventually reach the melting point and become liquid. Liquid water can change into gas without boiling. A puddle of water absorbs heat from the sunlight that strikes it, and slowly changes into water vapor, which is a gas. A liquid changing into a gas is called evaporation.

These processes also work in reverse. Water vapor can give off heat and become a liquid, which is called condensation. Condensation happens on the outside of a cold glass of water on a hot day. Liquid water can also give off heat and become a solid when it freezes into ice.

The following paragraph describes the water cycle. See if you can fill in the question marks with words or phrases that complete the sentences. If you don’t know the answer, roll over the question mark to see the correct word or phrase.

Water in the form of

snow and ice

? at the top of the mountain

melts

? and runs through rivers into lakes and oceans. The

sun

? heats the surface water, causing it to

evaporate

? , or turn from a liquid into a

gas

? called

water vapor

? . That water vapor floats up into the

atmosphere

? and cools down. Then, the water condenses and forms

clouds

? . As more water collects in clouds, it becomes

heavy

? and falls to the ground as

precipitation

? , where it collects as

snow

? at the top of the

mountain

? or adds

liquid

? water to rivers, streams, the ocean, or

groundwater

? .