Plants and the Water Cycle

Keeping Cool Interactive Slideshow

Keeping

Cool…Have you ever exercised so much that you started to…

Sweat?

Courtesy: Bill McKee, Earthdance.org

Courtesy: Larry Imperiale

Sweating is the way that our bodies keep cool. If we did not have a way to release the heat our bodies generate, we’d be in

trouble. In fact, heat stroke is a very dangerous condition that occurs when

your body is not able to keep cool.

Did you know that plants also “sweat”?

Plants transpire gases from small openings in

the surface of theirleaves called stomates.

These openings are emitting water vapor! This process of emitting water vapor through leaves is called transpiration.

To keep from getting hot and dying, plants transpire water through their leaves! We sweat (or perspire), and plants transpire!

Leaf as we see it

Leaf under a microscope

What would happen if plants didn’t transpire?

Well…look what happens to a teapot on a stove. This red teapot is full

of water. When water is heated, the energy (heat) moves from the stovetop, to the pot, to the water. The water gets hot, and turns into a vapor. Soon… you’ll see the steam coming from the spout!

But…What happens to a tea pot when you put it on the stove without any water in it? Yep! It gets

HOT!

Don’t try that one!

Looks like this teapot got toasty! See the crack from the heat?

Just like full teapots, most green leaves are full of water.

So when a stove heats up a full teapot, out

comes the water vapor.

The water absorbs the heat, which keeps the teapot from melting.

And when the sun heats up a nice green leaf, out comes the

water vapor!

The water absorbs the heat, which keeps the

leaf from dying!

And just like empty teapots, most brown leaves have no water.

So when a stove heats up an empty teapot, the teapot starts to

melt.

And when the sun heats up dry leaves on

plants, they start to get hot and die.

So, just like humans sweat to keep cool, plants on the earth do the same thing. Each of these trees in these pictures is transpiring water vapor (blowing off steam!) like a tea pot when they are warmed by the sun.

Photos courtesy of the Rainforest Foundation

What happens to the water vapor after it leaves a plant?

Here’s a hint:

Photo courtesy of the Rainforest Foundation

Photo courtesy of Tom Warner

And what happens to the water when it leaves a

cloud?

Here’s a hint:

Photo courtesy of Tom Warner

And where does some of the rain go?

Here’s a hint:

And where does some of the root water go?

Here’s a hint:

Hey! That picture looks familiar!

As the water travels through these different places, it forms a water cycle,

because it keeps moving with no starting or stopping point. And all

along the way, it keeps plants, animals, and people cool!

What would happen to the temperature of the earth if we didn’t have plants and water to help it keep cool?

Could we become a toasty tea pot?

Photos courtesy of NASA’s Earth Observatory