Plants and the Water Cycle

1
Plants and the Water Cycle Keeping Cool
Interactive Slideshow
2
Keeping Cool
Have you ever exercised so much that you started
to
3
Sweat?
Courtesy Bill McKee, Earthdance.org
Courtesy Larry Imperiale
4
Sweating is the way that our bodies keep cool.
If we did not have a way to release the heat our
bodies generate, wed 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?
5
To keep from getting hot and dying, plants
transpire water through their leaves! We sweat
(or perspire), and plants transpire!
Plants transpire gases from small openings in the
surface of their leaves called stomates.
These openings are emitting water vapor! This
process of emitting water vapor through leaves is
called transpiration.
Leaf under a microscope
Leaf as we see it
6
What would happen if plants didnt transpire?
Welllook what happens to a teapot on a stove.
But What happens to a tea pot when you put it
on the stove without any water in it? Yep! It
gets HOT! Dont try that one!
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 youll
see the steam coming from the spout!
Looks like this teapot got toasty! See the crack
from the heat?
7
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!
8
And just like empty teapots, most brown leaves
have no water.
And when the sun heats up dry leaves on plants,
they start to get hot and die.
So when a stove heats up an empty teapot, the
teapot starts to melt.
9
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
10
What happens to the water vapor after it leaves a
plant?
Heres a hint
Photo courtesy of the Rainforest Foundation
Photo courtesy of Tom Warner
11
And what happens to the water when it leaves a
cloud?
Heres a hint
Photo courtesy of Tom Warner
12
And where does some of the rain go?
Heres a hint
13
And where does some of the root water go?
Heres a hint
Hey! That picture looks familiar!
14
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!
15
What would happen to the temperature of the earth
if we didnt have plants and water to help it
keep cool? Could we become a toasty tea pot?
Photos courtesy of NASAs Earth Observatory