Air might be invisible but it is there. It is invisible stuff but seems to have a lot of push . Scientists have found out that it consists mainly of nitrogen and oxygen particles moving around in the the space between you and everywhere else. The space also contains carbon dioxide and a few other particles (we call the particles molecules).
This is a possible image of a sample of air consisting just of oxygen(blue) and nitrogen molecules (orange)
Why are they moving? Because they have energy. It make them move. You would move if you were given lots of energy. Remove the energy – reduce the temperature to -200 degrees centigrade and the particles would stop moving.
Is there water in the air around us?
Experiment – Put a saucer of water on a window ledge and watch for a day. What happens? Where has the water gone?
Maybe some of the water has escaped into the air that surrounds it. If this has happened we describe this as water turning into water vapour. The liquid water has turned into a gaseous water.
The water particles or water vapour molecules (blue and red particles) are being pushed around by the air particles which keep them ‘floating’.
How much water is in the air that is floating around us?
Experiment. Fill a beaker with crushed ice, cover the top with cling film and observe what happens.
Think about what has happened. Why did the water leave the air?
Another important observation that you need to make is what happens to hot air?
Experiment. Create a paper spiral and hang it over a source of heat. You could try a ‘hot water bottle’
DO NOT USE A FLAME – IT WOULD BE VERY DANGEROUS
What happens? Does anything happen?
If hot air rises then the water particles that are ‘trapped’ in the hot air will rise as well. The air gets cooler as it rises. The water vapour becomes very small water droplets. Small enough to still be ‘trapped’ by the energetic moving air molecules. A floating cloud is formed.