This is a glass of water and it's been on a long long trip. I'm serious.

It didn't pack any bags or take selfies along the way but this water has been around the world many many times. 

(Intro)

Think I'm crazy? I'm not. This water is part of a long worldwide system called the water cycle. The water cycle explains the way water moves on, above and below the Earth. And it's huge! It includes every giant glacier and every tiny little puddle. It includes the water at the bottom of the ocean and the water in the clouds in the sky.

As you know, water is matter and we've learned that matter can change states. It can be a solid, a liquid or a gas. For water that means it can be ice, liquid water or water vapor. And as all of this water which makes up the hydrosphere wind it's way around the world. It interacts with the other three spheres. It starts, as many things do, with the Sun. Hey buddy.

(Big Question)

As the sun sends it's energy down to the earth, the surface of the oceans and lakes are heated until some of the liquid water turns into a gas: water vapor. This process is called evaporation. Have you dried off in the hot sun after a dip in the pool? If you have, you've experienced evaporation. 

After the water evaporates, the water vapor rises higher and higher into the atmosphere. As it goes up, it starts to cool, which makes a lot of of sense. You've probably noticed that the tops of tall mountains are cold and snowy, sometimes even in the summer.

So as the water vapor rises, it eventually gets cooler and starts to turn into liquid. This is called condensation. All those little water molecule start sticking together, along with the particles of dust and other tiny bit of stuff, turning into a mass of small drops of condensed water that we call clouds. And when it's all snuggled up in the clouds, water can do some serious traveling, because wind and other air currents can push clouds over long distances. So the water in the clouds above you may have originally been picked up over a faraway ocean. 

Now if enough water particles in the cloud stick together, then the water would fall out. And when it does, it's called precipitation. It takes millions of cloud droplets to produce just one raindrop. If the clouds are cold enough, the can form other kinds of precipitation too. Ice crystals can form in the clouds, for example, going bigger and heavier until they fall in the form of snow, sleet or hail.

No matter what form it takes though, once the water falls, it can go in a couple of different routes. Some of the water will hit the ground and run toward streams and rivers, where it will eventually join the ocean. Some of it will soak into the ground through tiny pores in the soil. This water can collect and hang out underground for years until it slowly moves into the sea, or it can be pumped up to be used as drinking water. And some of that water that rained down will also quickly be evaporated again. 

This whole process, evaporation, condensation and precipitation is repeated over and over, moving water all around the world empowering weather events. We have the water cycle to thank for hurricanes, blizzards and that rain storm that caught me outside without an umbrella the other day. But you can also watch the water cycle happen in your own kitchen. Let's investigate. 

(Investigation)

First pour hot water into a clean bowl, then cover it with plastic wrap and place a few ice cubes on top. In this experiment, the hot water is water that has been heated by the sun and the wrap with the ice cubes is the cool atmosphere.

Molecules in the hot water rise in the form of water vapor. Once they hit the cool atmosphere, which is our plastic wrap, you can see the molecules condense on the underside of the wrap into drops of liquid water. Once there's enough condensation, water droplets will fall back into the bowl, it raining. You've just created a tiny adorable water cycle all on your own.

(Conclusion)

Let's cycle back and review what we've learned. Energy from the Sun powers the water cycle, a process that moves water around the globe through evaporation as the water rises, condensation as it forms in the clouds, and precipitation as it falls back down in the form or rain, snow, sleet or hail. Water the most through the system over and over again, changing forms and visiting every corner of the earth. I bet you've got a whole new respect for this glass of water, huh?