Science
Welcome to the water of earth!
The water that flows through you is the same water that has flowed on Earth since the very beginning. You are part of a cycle that has been going on here for billions of years!
States of Water
Drop knows how to handle all sorts of situations! She can change shape as necessary, and she has three distinct forms, or states:
Liquid
Go with the flow! This is when Drop gets to be in the oceans, rivers, lakes, ponds, swimming pools, bathtubs, buckets and your lemonade! Drop spends most of her time, about 98% of it, being liquid.
Solid
Hold still. This is when Drop crystalizes into snow or ice. In the cold clouds, she can form into unique snowflakes with six perfect points. She can ball up into hail as she flies up and down in the clouds. She can harden into solid icicles and freeze over ponds. Once she is solid, Drop can be rolled up into snowballs or carved into sculptures. She can be frozen into little cubes and added to your lemonade! And she can be stuck in rocks and glaciers for thousands and thousands of years! About 2% of all Earth’s water is frozen.
Gas
S T R E T C H ! ! This is when Drop bounces right into the air and grows 1700 times her size! She is invisible in this state, called water vapor, and she floats around the air this way for some time. Drop stays afloat as vapor for about 10-15 days (on average) before condensing into liquid. As she condenses back into liquid, she forms tiny droplets that make clouds. Steam, like clouds, is also floating visible liquid water droplets, and not water vapor. Water vapor really is invisible!
So how can we see water vapor? We can’t! But when you look at a tea kettle whistling, you can see a small gap between the hole of the kettle and the steam forming in the air—that gap is the invisible water vapor. And why does that kettle whistle? Water vapor is rushing to get out! Drop grows so much and so fast when she turns to vapor that she has to rush out of that kettle to find room to stretch!! (And kettles are designed to whistle!)
What makes water move from state to state? Temperature and pressure. Drop is always moving from high to low and back again. When water boils, the temperature is so high, Drop can’t stand it anymore and she vaporizes into the air, or evaporates. But how does your towel dry hanging on a hook? It’s not boiling hot but it still dries eventually. So how does that work? Well, that’s because of pressure. The surrounding air is lower pressure than water and it pulls water into it. If the air is moving, it creates even lower pressure, which dries even faster. That’s why your lips get so chapped on a windy day! All that low-pressure air is pulling the water right out of them!
When the temperature is low, and the pressure is high, Drop condenses or freezes, depending on how cold. Your cold can of soda collects water on the sides as water from the air condenses on it. If the air outside is colder than your soda, you will not see those droplets form. And if your can is freezing, you will see frost form on the outside of it!
Do other things change state?
Yes! Water is the only thing on Earth that changes into its three states naturally. That is because water’s boiling point and freezing point are within the natural temperature and pressure range of our planet. But if our planet got super hot and super cold, we would see all sorts of things change state! Every element, from gold to oxygen to mercury, can be a liquid, solid, and gas under the right conditions.
Water Cycle
From the sky to the sea, Drop has seen it all! She knows everything there is to know about the water cycle.
The water cycle starts with the sun.
Energy from the sun lifts water into the air, changing it from liquid to gas. (As water moves from liquid to gas, it expands about 1700 times its size!) This process of expanding from water to vapor is called evaporation.
When water vapor floats around in the air, it is called humidity. Sometimes you can feel how humid the air is when there is a lot of water vapor floating around. Warm air can hold more water vapor than cold air.
As water vapor cools, it forms millions of tiny liquid droplets. This process of turning back to liquid from gas is called condensation. Still floating in the air, these droplets make clouds. When droplets rest on the ground, they make dew.
As water droplets squish into each other, they grow. Once they are too heavy to float anymore, they fall as raindrops. Water that falls from the sky is called precipitation. Sometimes it freezes into hail or snow. Rain, hail, and snow are all forms of precipitation.
When water falls on land, some of it washes off as streams and rivers, called runoff. Some water soaks into the ground. This is called infiltration. Water that is in the ground is called groundwater.
Plants drink in groundwater through their roots, use it to grow, and then release it as vapor from their leaves. This is called transpiration. Most of the water that plants take in through their roots (about 99.5% of it!) eventually comes out of their leaves through transpiration. And plant transpiration makes about 10% of Earth’s water vapor.
Snow and ice can also disappear into the air without melting first. This is called sublimation. You can see this happening in your own freezer when the ice cubes in the tray shrink. If you leave ice cubes in the freezer long enough, they’ll vanish completely!
And when water finds a place to rest in lakes and oceans, it is called collection or storage. Anywhere water collects, even tiny puddles on leaves, is part of the water collection process. And from there, water evaporates and the whole cycle starts again!
Water Facts
Though it looks clear in small amounts, water is actually blue. Water absorbs red light more than other colors, and reflects blue the most. So the more water you can see, the bluer it looks!
About 71% of the world’s surface is covered by water. And most of that water—about 96.5% of it—is in the ocean. The rest is in the ice, the air, and where water collects on land, underground, and in living creatures.
Did you know that there are about 2000 storms occurring around the planet at any given moment?! Water is always on the move! It cycles in and out of the sea, the sky, and life itself!
Every time you drink, the water that enters your body helps your body stay alive and in flow. You are also part of the water cycle!