Science 101: Why does air expand when you heat it, and why does hot air rise?by: William C. Robertson, Ph.D.

Journal ArticleDigital resources are stored online in your NSTA Library.

The short answer to the questions in the title are that air doesn't necessarily expand when you heat it, and hot air doesn't always rise. These two commonly misunderstood concepts related to the behavior of gases and how this behavior applies to physical situations, including weather. The article delves more deeply into expanding air and hot air rising.

  • Elementary
  • Middle
Publication Date

Community ActivitySaved in 319 Libraries

Reviews (3)
  • on Thu Jul 07, 2011 12:25 PM

Most people use incorrect explanations or misconceptions to explain these two events common in the natural world. That is why reading this article completely and carefully is so very important. Under certain conditions the statements are true but under other conditions they make no sense. This is a must read for all teachers so that what we teach in the classroom is the best and complete explanation.

Adah  (San Antonio, TX)
Adah (San Antonio, TX)

  • on Mon Dec 09, 2013 3:55 PM

The article is useful in reviewing the basic physics behind fluid motion. The visual aides help in "seeing" the molecules behave with more heat energy. Thank you for the work.

Emebet Bryan
Emebet Bryan

  • on Thu Aug 18, 2011 7:52 PM

Dr. Robertson provides an excellent explanation on the misconceptions for both questions in a way that helps teachers understand the behavior of gases and the application to weather. This is not an easy to digest article, you are going to have to spend some time thinking it through. Once you understand the examples, you will come away with a little more understanding of the concepts.

Sandra Gady  (Renton, WA)
Sandra Gady (Renton, WA)

Free - NSTA Members

$1.29 - Nonmembers

Login or Create a Free Account to add this resource to your library.