- What does air temperature show?
- What happens to air particles when the air warms up?
- Why does warm air rise up?
The heat level of air is the air temperature
Clean air is a colourless, odourless, and transparent mixture of gases. In addition to these, the air has other important properties.
We have learned that the distances between the molecules of matter are large in the gaseous state, so the molecules can freely move around. When the substance heats up, the particles start to move faster; when they cool down, their movement slows down. Determining the speed of particles is a difficult task. And besides, there are very, very many of these particles. It is much easier to know how hot or cold a thing is when we measure its temperature. The warmer an object is, the higher its temperature. The air also has a temperature, or level of heat. To measure this, the thermometer must be placed where the air can freely enter, but shielded from the sun's rays.
When an object is heated, its particles start to move. The faster the particles of a substance move, theits.
Air expands as it warms up
One other property of air is related to air temperature. It is thermal expansion, which is common to all other gases as well as solids and liquids.
An experiment that shows how the air expands upon heating and contracts upon cooling requires two containers (one with hot water and the other with cold water), an empty bottle, and a balloon. For best results, keep the bottle in the freezer for half an hour before testing. Stretch the mouth of the balloon over the mouth of the bottle and immerse the bottle in hot water. When the balloon is inflated, place the bottle in cold water (preferably with ice cubes). What happens?
As the air warms, the particles begin to move faster and move away from each other, so they take up more space.
When air is heated, particles start to moveand moveeach other. This causes air to .
When air is cooled, particles start to moveand moveeach other. This causes air to .
Think!
- Why does air expand as it warms? Are the air particles getting bigger?
Warm air rises up
There is another interesting phenomenon related to the thermal expansion of air. As the air expands, the arrangement of the particles becomes less dense, and therefore warm air is lighter than cold air. Cold air, which is heavier and denser, thus pushes up warm air.
In the picture used as an example, the heated air from the radiator (fireplaces too) starts to move upwards. As the air rises, the place where it used to be fills with more cold air, which in turn heats up and rises. In this way, the heat is distributed throughout the room.
Cold air is ... than warm air.
- lighter
- heavier
- more dense
- less dense
Think!
- Why is the central heating radiator placed close to the floor instead of under the ceiling?
- Why do we use underfloor heating in bathrooms, and not ceiling heating, for example?
Bonus: Hot air balloon
A hot air balloon can lift a small group of people into the sky. The hot air balloons are made of dense fabric. Below is an opening through which gas burners heat the air. At the top of the balloon, there is a valve that can open and close. From there, hot air can be released from the balloon and thus descend to land.
I now know that…
Air temperature is the heat level of air, and it is measured with a thermometer. Air expands as it warms, a phenomenon called thermal expansion. Warm air is lighter than cold air, so it rises.
- Palvelun tarjoaa Star Cloud OÜ