Presentation on theme: "/ / / Mr. Harpers science mini- lesson with read-along audio Click on the speaker icons to hear the spoken words."— Presentation transcript:
/ / / Mr. Harpers 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. Thats why a wet sidewalk gets dry quickly when the sun comes out. Heat is what makes water evaporate.
We cant see water vapor in the air because its invisible, but its always there as part of the air around us.
About 75% of Earths 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 doesnt 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
If you are a 4 th of 5 th 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. evaporation condensation precipitation runoff
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.
is the water that runs downhill. Sooner or later the ice and snow melt. Any precipitation water that doesnt soak into the ground or get used by plants and animals runs downhill toward the ocean as runoff. 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 5 th grader, you should know the four steps of the Water Cycle….
1.Evaporation 2.Condensation 3.Precipitation 4.Runoff Liquid water becomes part of the air By the time you are a 5 th grader, you should know the four steps of the Water Cycle….
1.Evaporation 2.Condensation 3.Precipitation 4.Runoff Water vapor cools and becomes liquid. By the time you are a 5 th grader, you should know the four steps of the Water Cycle….
1.Evaporation 2.Condensation 3.Precipitation 4.Runoff Water droplets get heavy and fall. Rain, snow, sleet. hail By the time you are a 5 th grader, you should know the four steps of the Water Cycle….
1.Evaporation 2.Condensation 3.Precipitation 4.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 Earths 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 cant 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 cant drink salty ocean water. The plants we need for food cant live with salty water. Animals on land need a lot of fresh water with no salt in it.
Salt water wont 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 Earths 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 suns 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 theres 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.
Dont 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.
Dont take super long showers. Its important to stay clean, but some people waste a lot of water when they shower.