Heat rises, so right away the hot air and water vapor, water in a liquid form, is going to work its way to the top of our container.
The hairspray that we added acts a what’s called cloud condensation nuclei (CCN). CCN in our atmosphere is often dust or pollutants floating around. This is important because as the water starts to condense, it needs something other than just water droplets to latch onto to form a cloud.
As the warm air and water vapor rise, it not only is stopped by the lid, but it begins to cool down because the ice. As it cools, it will also condense giving us a cloud!
In the process, you might also see some condensation, which is the water vapor (gas) turning back into a liquid water.
This experiment not only shows us the general way that clouds form, but why sometimes we’ll see big fluffy clouds build in during the heat of the afternoon, especially on a hot summer day.