Water is restless; it likes to move. Gravity makes it flow downhill, off your roof, into creeks, down rivers and even over giant waterfalls. Some water sinks into the ground, but most of it ends up filling the oceans, which cover over two-thirds of the planet.
The water cycle doesn’t end in the oceans though. Water at the sea’s surface is able to defy gravity and climb back up into the sky. How? Because water isn’t always a liquid. You know that in really cold weather, or your freezer, water can freeze into a solid that we call “ice.” But in warm or dry weather, water can evaporate into an invisible gas. We call that gas “water vapor.” When the air has a lot of water vapor in it, we say it is humid. Florida is humid most of the year!
Water vapor can rise up and then condense into tiny droplets that form clouds. From those clouds, water can fall back to the ground as rain or snow, which keeps the restless water cycle flowing.
What’s the invisible part of the water cycle that’s important to people all over the world?