WATER, AIR AND SOIL

1. WATER

- Why is it very important?

All living things need water. Animals and people drink water and plants absorb water from the roots. If we don’t have water we will die.

- Where can we find water?

Most of the water on the Earth is found in the sea.

There is also water on land. This is the water that we use for drinking and watering the plants.

-       Surface water: rivers, lakes, …

-       Underground water.

States of water

Water can be found in three different states:

-       Liquid state: river, sea,…

-       Solid state: ice, snow.

-       Gaseous state: Steam water

WATER CYCLE 

The Earth has a limited amount of water. 

That water keeps going around and around in what we call the "Water Cycle".

This cycle is made up of a few main parts:

Evaporation: Heat from the Sun makes water to evaporate (turn from liquid into gas) and rise into the sky.

Condensation: Water vapor in the clouds cools down and it becomes water again.

Precipitation: Water falls from the sky in the form of rain, snow, hail.

Collection: Oceans and lakes collect water that has fallen. 

AIR

What is air?

Air is a mixture of gases which surround the Earth.

There are three main gases in the air:

-         Nitrogen: most of the air is made up this gas

-         Oxygen: the second most important gas in the air.

-         Carbon dioxide: There is not much of this gas in the air.

Properties of air

-         Air has weight.

-         Air occupies space.

-         Air does not have its own shape.

-         Air moves. It is called wind.

Where can we find the air?

We can find air in the atmosphere.

The atmosphere is a layer of air that surrounds the Earth. It has two parts:

1)   Lower part: here we can find oxygen, wind and rain.

2)   Upper part: Here we can find only a few oxygen and we could not breathe in this part.

SOIL

What is soil?
Soil is a layer of earth mixed with water, air, and plant remains

Types of soil
Soil can be:
- Fertile: It has enough water an food for plants. Many plants can grow in this type of soil.

- Poor: It has little food for plants. Only hardy plants like olive trees can grow here.

- Arid: It has very little water and it is made up of rocks and sand. Only plants that need very little water, like cactus, can grow here.