Transcript The Water Cycle - Pacoima Charter School

Mr. Harper’s science mini- lesson
with read-along audio
Click on the speaker icons to hear
the spoken words
All water is made of tiny, tiny particles
called molecules, way too small to see.
several ways to draw water molecules
When these molecules get cold they
slow down and freeze solid. Frozen
water is called ice and can be like rock.
The molecules in any solid
substance are stuck together.
Solid things do not easily change
shape or size.
If ice gets warmer it melts and becomes
liquid. The molecules move faster and
begin to slip and slide past each other.
The molecules in a liquid
substance can slide by each
other and change shape.
This is why liquid water
changes shape so easily
and can go through
small places.
As liquid water gets warmer the molecules begin
to float up and away from the liquid and become
gas (part of the air).
The molecules in a gas
substance float and
stay apart from each other.
Water molecules in the air are called vapor.
The process when liquid water changes into
vapor is called evaporation.
Evaporation is what happens when water
in an open container seems to disappear
after a few days.
The more water
is heated, the
faster
evaporation
happens.
When the
temperature gets
hotter, evaporation
happens faster.
That’s why a wet
sidewalk gets dry
quickly when the
sun comes out.
Heat is what makes water evaporate.
We can’t see water vapor in the air
because it’s invisible, but it’s always
there as part of the air around us.
About 75%
of Earth’s
surface is
covered by
ocean water.
Every day as the sun warms the oceans, many
tons of water molecules evaporate and
become gas vapor in the atmosphere.
Heat is what makes water evaporate.
Water vapor high in the sky can cool
and condense into tiny floating
droplets of liquid water.
Large groups of liquid droplets are
what clouds are made of.
The clouds and vapor are blown
by winds all over Earth.
Some of it moves over land.
When clouds get colder the
droplets get bigger. This makes
the clouds look darker.
When the droplets in clouds
get too big and heavy to float
they fall to the ground as rain.
Some of the rain that falls soaks into the
soil to give water to the trees and plants.
Some rain water
seeps deep
underground
and collects as
groundwater
that people can
get when they
dig a well.
When it gets really cold, rain turns into
snow. Sometimes snow and ice can lay
on the ground for a long time.
Rain that doesn’t soak into the ground,
or freeze into ice and snow will run
down hill toward the ocean.
Streams flow together and get bigger
as they move toward the ocean.
This runoff water keeps
moving downhill until it
flows into the ocean.
The sun warms the ocean and the water cycle
keeps going, just like it has for billions of years.
Every water molecule on Earth has
gone around this Water Cycle many,
many times in the past.
vapor
You can learn more about The
Water Cycle on
If you are a 4th of 5th grader, or a younger
student who really likes science, this
program continues. Just keep clicking.
There are four steps of the Water Cycle
that we should all know.
• evaporation
• condensation
• precipitation
• runoff
Evaporation is when liquid water
that has been warmed by the sun evaporates and
becomes vapor, a gas in the air.
Condensation
You can see condensation on a cold soda can
when the air near the can gets cool and the
vapor in that air turns to liquid.
When clouds get cooler, the droplets
condense into bigger drops. When the
condensation gets too heavy to float,
it will fall to the ground.
Precipitation is when water
falls from the sky. If it is warm enough to be
liquid, we call it rain.
When the air is colder the precipitation
freezes and becomes snow.
Sometimes cold precipitation falls
as beads of ice called sleet.
Sometimes
precipitation
gets blown by
updrafts up
high where the
air is very cold.
Balls of ice get
bigger as the
wind pushes
them up.
When the ice balls fall they are called
hail. Big hail stones can be very
dangerous.
Runoff
is the water that runs downhill.
Sooner or later the ice and snow melt.
Any precipitation water that doesn’t soak
into the ground or get used by plants and
animals runs downhill toward the ocean
as runoff.
Runoff streams join together until they
form huge rivers that flow into the ocean.
The Water Cycle keeps going around
and around. The cycle never stops.
By the time you are a 5th grader, you
should know the four steps of the
Water Cycle….
By the time you are a 5th grader, you
should know the four steps of the
Water Cycle….
1.
2.
3.
4.
Evaporation Liquid water
Condensationbecomes part
Precipitation of the air
Runoff
By the time you are a 5th grader, you
should know the four steps of the
Water Cycle….
1.
2.
3.
4.
Evaporation
Condensation
Precipitation
Runoff
Water vapor
cools and
becomes
liquid.
By the time you are a 5th grader, you
should know the four steps of the
Water Cycle….
1.
2.
3.
4.
Evaporation
Condensation
Precipitation
Runoff
Water
droplets
get heavy
and fall.
Rain, snow, sleet. hail
By the time you are a 5th grader, you
should know the four steps of the
Water Cycle….
1.
2.
3.
4.
Evaporation
Condensation
Precipitation
Runoff
Water flows
back to the
ocean.
Wow, you just learned a lot about
The Water Cycle!
You must really be interested in science.
But if you want even more science……
…just keep on clicking that mouse
All living things on Earth
must have water to live.
Some plants and animals only
need a little water to survive.
Other plants and animals need a
lot of water in order to survive.
Earth has a lot of water, but
almost all (97%) of Earth’s
water is salty ocean water.
This is fine for
plants and animals
that live in the sea.
Salt water is OK
for them.
But people can’t drink saltwater. People
must have “fresh” water with no salt in it.
All plants and animals that live on land
need fresh water to live.
People can’t drink salty ocean water.
The plants we need for food can’t live
with salty water.
Animals on land need a lot of fresh
water with no salt in it.
Salt water won’t kill you if you get a
little bit in your mouth at the beach.
But if all you had to drink was ocean
water you would get very sick and be
dead in just a few days.
If most of Earth’s
water is salt water,
where can we get
enough fresh
water to live?
Lucky for us, when salt water
evaporates only the fresh water
molecules become water vapor. All
the salt stays behind in the ocean.
When the sun’s heat evaporates ocean
water only the fresh water molecules
become vapor that forms into clouds.
That means that all the water in
clouds is fresh water.
And all the water in
rain is fresh water.
And all the water in the soil and
underground is fresh water.
And all the water in streams,
lakes, and rivers is fresh water.
So there’s plenty of fresh
water, right?
Not really, There are 7 billion people on this planet
that all need fresh water. If everybody wastes fresh
water there might not be enough.
But there are things we can do to help
conserve our important water resources.
Don’t let the water run while you
brush your teeth.
We only really need a little bit to wet the brush, then at
the end to rinse our mouth and the toothbrush.
Don’t take super long showers.
It’s important to stay clean, but some people
waste a lot of water when they shower.
Please don’t waste water.