Our Smartmedia series is intended to make you smarter by explaining the world. If you want to learn all the basic knowledge this series is perfect for you.
In this episode we discuss air and water.
The Earth is wrapped in a layer of air, called the atmosphere. Air is made of several different gases, one of which is oxygen which people and animals need to breathe to stay alive.
Air is all around you, but you can’t see it. You can feel it, but only when the wind is blowing against you. The wind is moving air.
Air does not have any special shape. It spreads out in all directions and is everywhere.
If you continually blow air into a balloon, it will eventually burst as the air pushes inside the balloon.
A falling parachute traps air underneath it. The air pushes up against the parachute, making it fall slowly.
When air is heated, it expands and takes up more space. It is lighter than the cold air around it and rises upwards. Hot air balloons lift off the ground because hot air inside them makes them lighter than the air around them.
A gas burner heats the air inside the balloon. When it is switched off, the air inside it cools and the balloon lands.
Trapped air stops heat escaping. Wool clothes keep you warm because woollen fibres trap lots of air.
Birds fluff up their feathers in winter to trap air under their feathers to keep them warm.
Air presses against you, but your body is made in such a way that you don’t feel the weight.
Water is liquid. It has no shape of its own, but takes the shape of whatever is holding it.
If water is poured into a glass it will fill the glass, and become the same shape as the inside of the glass.
If water is spilt on the floor, it runs all over the place, because it has nothing to keep it in a particular shape.
A puddle of water will dry up on a sunny day. The water does not really disappear. It turns into tiny drops, too small for you to see.
The drops, called water vapour, rise into the air. When water turns into vapour and rises into the air, it is called evaporation.
The air is full of water vapour, because heat from the sun makes water evaporate from the sea, lakes and rivers.
As water vapour rises it reaches cold air high in the sky. It turns back into tiny drops of water which join to make clouds.
As the drops get larger they fall to the ground as rain. Water vapour turning into water again is called condensation.
If you stand in a swimming pool with water up to your neck and arms by your sides, your arms will slowly rise. The water pushes them up.
An iron ship floats because it contains air, which is lighter than water. As the ship pushes aside water, the water pushes back, holding the ship afloat.
That was all about air and water! Make sure you check out http://www.pythes.com for more interesting and cool stuff. Subscribe and click on the notifications button so that you don’t miss the next episode of Smartmedia.