On Hot Air

Although we don’t mean to make generalizations inaccurate, they are not the full story. After all, these statements are, by definition, generalizations. Sometimes people generalize the generalization, but failing to remember that continual generalization moves one further from the truth – thus eventually turning the generalization into misinformation that leads to misunderstandings.

Repeat after me – Hot air does not rise.

Just to make sure, let’s try again – Hot air does not rise.

Regardless of the links you can provide to the contrary, or ever provide a reference for a reputable textbook, hot air does not rise – it never has and I very much doubt ever will. Yet, how many times have we heard or said, Hot air rises? (Yes, I cringe when I hear TV weather forecasters use it.)

Nah baby nah … hot air does not levitate. Hot air does not move upward on its own – It is pushed upward by more dense cold air that displaces it – Just has bathtub water level moves upward on the sides when one takes their seat in a bathtub. However, there is no need for you to run down the street naked like Archimedes yelling, Eureka, eureka, I found it!

Here’s the story. During my science teaching days, we were preparing a lesson for the next day. Because my colleague had not seen this activity, he took one set of the materials to the location of the ice machine – the boys’ locker room.

My colleague returned saying it worked great, but shared an interesting story. One of the physical education (PE) teachers watched without knowing any details, and then said, “This means hot air doesn’t rise.” Bingo! Meanwhile, this gave me an opportunity to have some fun with the good-natured PE teacher.

During the eventually discussion with the students after the activity – and knowing students would quickly deliver my comment – I stated, “If a PE teacher like Mr. X can figure this out on his own, surely this is easy to understand.”

We had fun with it through the years, for as students are so predictable. But the point remains the same – Hot air doesn’t rise because it is pushed upward when it is displaced by more dense, colder air.

By the way, here’s a similar activity – but ours was better. Yo, Starla, show Navar.