Skip to 0 minutes and 7 seconds A lot of weather in the atmosphere is driven by the fact that warm air rises. And there’s a lovely demonstration of this that you can try at home. All you need is a tea bag, the sort that comes with a tag attached, some matches, and a heat proof tile, or a plate, or anything like that that’s heat proof. What you need to do is you need to take the tag off the tea bag and empty the tea out. What you should be left with when you do that, is a cylinder of tissue paper. So you open it up, and you have a cylinder of tissue paper.
Skip to 0 minutes and 41 seconds Now you probably need to be indoors to do this, and it needs to be draft free. So no open windows or doors anywhere near. Then you should be able to stand the tea bag up on its end, and set fire to it at the top.
Skip to 0 minutes and 59 seconds As the tea bag burns down, there’s warm air being generated above it, which is creating a lift effect. And the tea bag’s getting lighter as it burns down until eventually it takes off. So how does this relate to the atmosphere? The motion of the Earth’s atmosphere and oceans is driven by thermals, hot air rising. The large scale circulation of the atmosphere redistributes heat for the sunny tropics to the less sunny polar regions. All sorts of weather systems from land and sea breezes, to hurricanes and tornadoes, are the result of warm air rising. You can sometimes see thermals in the atmosphere if you watch birds or gliders being carried upwards, or by watching a puffy cumulus cloud blow out.
Many weather systems, including land and sea breeze and hurricanes, are the result of hot air rising. To illustrate, Sylvia shows you a simple practical demonstration using a teabag, matches and a heatproof tile that you can try for yourself at home.
If you’d like to complete this experiment, please be aware of the potential fire risk and take care when using the matches. We recommend you complete the experiment well away from flammable materials, within a room with a high ceiling.
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