Air and Water

18.1 The Oxygen and Carbon Dioxide Cycle
Living things need a constant supply of oxygen and carbon dioxide in the air to survive. All living things need Oxygen and Plants need carbon dioxide. It goes through a cycle called the The Oxygen and Carbon Dioxide Cycle

Oxygen in the Air                   Carbon Dioxide in the air
Oxygen will not run out as there are plants.          Plants take in Carbon dioxide to do photosynthesis
When plants do photosynthesis oxygen is            dead animals or humans could produce carbon    
produced. In this way, oxygen is used up            dioxide.  Burning of fossil fuels and vehicles could also produce
by living things is replaced constantly.                  carbon dioxide.

The air around us is made up of:

                      Nitrogen
                      Oxygen
                      Carbon dioxide and other gases                                            Water vapor            
                    




18.2 The Water Cycle
Water never runs out on earth due to the water cycle. The water cycle is the continuous movement of water from the earth, to the sky and back to the Earth. Here is the Water cycle:

1. Rising into the Sky
The Water rises into the sky, it evaporates to the sky. This effects because of the Sun. The sun causes Lakes, Rivers, Reservoirs, Oceans and even water that is released by living things.

2. In the Sky
When the water vapor rises to the sky, it cools and condenses to form tiny droplets of water. When the tiny droplets of water gather, It turns into a cloud.

3. Falling Down
When the clouds have exceed the limits to gather the tiny droplets of water it becomes a nimbostratus cloud or should I say 'black clouds'. Then when the cloud is getting more heavy, the tiny droplets starts to fall as rain.

Importance of the Water Cycle
  Many living things need fresh water for their survival. This is important because we can know what are clouds made of then why there is rain.

  Human activities cause great harm to our environment. They also affect the water cycle.
Here are the examples for water cycle:

1. Deforestation

Deforation is the cutting of trees. Many trees are cutted know because humans are selfish. Deforestation contributes to global warming. Deforestation causes floods, landslides and an increase in the Earths temperature.







2. Burning of Fossil Fuels

Burning of fossil fuels in places such as factories, produces harmful gases that form acid when they mix with water. When it rains the gas will mix with with the rain creating an Acid Rain instead of normal rain. Acid rain can pollute the water bodies and can kill plants on Earth.




Experiment about water cycle:Workbook Page 37-38
18.3 A Mini Water Cycle
Materials needed:Ice Cubes, Petri dish, Beaker, Hot Water.


Steps:
1.Pour water inside the beaker.


2.Place the Petri Dish above the beaker.


3.Place a few ice cubes above the petri dish.


Explanation:
You can observe that the hot water inside the beaker evaporates until the base of the petri dish. When it reach the petri dish, it condenses to form tiny droplets of water. then when the base of the petri dish is heavily filled with water droplets, the water droplets will fall.