Lesson: Convection

(Grades 9-12)

To produce a visual convection current in the classroom and compare it to the images taken of convection cells in the Sun.

Teacher Information

Convection is the transport of energy due to density differences when not in a free-fall (microgravity) environment. As a liquid or gas is heated it expands and becomes less dense and therefore lighter. If a cooler denser material is above the hotter layer the warmer material will rise through the cooler material to the surface. The rising material will dissipate its heat (energy) into the surrounding environment, become more dense (cooler), and will sink to start the process over.

The source of the Sun's energy is the nuclear reactions that occur in its core. There, at temperatures of 15 million degrees Kelvin, hydrogen atom nuclei, called protons, are fused and become helium atom nuclei. The energy produced through fusion in the core moves outward, first in the form of electromagnetic radiation called photons in the so-called radiative zone. Next, energy moves upward in photon heated solar gas. This type of energy transport is convection. Convection motions within the solar interior generate magnetic fields that emerge at the surface as sunspots, and loops of hot gas called prominences. Most solar energy finally escapes from a thin layer of the Sun's atmosphere called the photosphere, which is the part of the Sun observable to the naked eye. Convection cells can be seen on the surface of the Sun like the image that follows.

The activity is a simulation of this image.

Activity: Displaying Convection


Type of Activity:


  1. Place the container with the fluid on the hot plate on the lowest setting.
  2. Within a couple of minutes you should see a reaction. If the reaction starts to dissipate, increase the heat by a very small amount.


  1. Why does the reaction dissipate?
  2. Would this dissipation happen on the Sun? Why?
  3. Does your observation of the simulation coincide with the image above?
  4. Remembering why convection occurs, would this occur in a microgravity (free-fall) environment?

Related links:

Connections to the National Standards:
(Grades 9-12)

*NOTE - apple cider will work for this activity but a better material is Rheoscopic Fluid by Novostar Designs, Inc. Burlington, N.C. 1-800-659-3197. The listing of the proprietary name in this section is not an endorsement of the product. The company name listed is only a suggestion.
Created by: Dennis Christopher
Direct Comments to: therese.a.kucera@nasa.gov