what's water cycle？什么是水循环

The?Water?Cycle

Water?on?Earth?is?always?changing.?Its?repeating?changes?make?a?cycle.?As?water?goes?through?its?cycle,?it?can?be?a?solid?(ice),?a?liquid?(water),?or?a?gas?(water?vapor).?Ice?can?change?to?become?water?or?water?vapor.?Water?can?change?to?become?ice?or?water?vapor.?Water?vapor?can?change?to?become?ice?or?water.

How?do?these?changes?

happen?Adding?or?subtracting?heat?makes?the?cycle?work.?If?heat?

is?added?to?ice,?it?melts.?If?heat?is?added?to?water,?it?evaporates.?

Evaporation?turns?liquid?water?into?a?gas?called?water?vapor.

If?heat?is?taken?away?

from?water?vapor,?it?condenses.?Condensation?turns?water?vapor?into?

a?liquid.?If?heat?is?taken?away?from?liquid?water,?it?freezes?to?

become?ice.

The?water?cycle?is?called?the?hydrologic?cycle.?In?the?hydrologic?cycle,?water?from?oceans,?lakes,?swamps,?rivers,?plants,?and?even?you,?can?turn?into?water?vapor.?Water?vapor?condenses?into?millions?of?tiny?droplets?that?

form?clouds.?Clouds?lose?their?water?as?rain?or?snow,?which?is?called?

precipitation.?Precipitation?is?either?absorbed?into?the?ground?

or?runs?off?into?rivers.?Water?that?was?absorbed?into?the?ground?

is?taken?up?by?plants.?Plants?lose?water?from?their?surfaces?as?

vapor?back?into?the?atmosphere.?Water?that?runs?off?into?rivers?

flows?into?ponds,?lakes,?or?oceans?where?it?evaporates?back?into?the?atmosphere.

The?

cycle?continues.