8+
Gallery 8

Convection

The convection current exhibit, consisting of a display table with a silver pole in in the centre, a black framed glass window, and then a white screen showing convection shadows.
A white screen showing the shadow of convection currents on the screen.

Convection currents in water (or air), create cooling and heating cycles of movement.

How it works

Press a button to change the position of a heat source at the base of a clear water tank and watch how convection currents move through the water.

Things to try or ask around the exhibit

  • Does this remind you of how water moves in a boiling pot of water?
  • Try pressing both outer buttons and watch how the currents move.

Background

The circulating fluid shadows that you see on the back wall are convection currents, caused by heating and cooling fluid.

Convection currents in water (or air) cycle around as water cools down and warms up. Water at the top of the tank cools down, which makes it more dense so it sinks. As it sinks, it pushes warmer, less dense water sitting at the bottom of the tank upwards. When the cool, dense water reaches the bottom, it warms up and becomes less dense, so it rises and the cycle of cooling and sinking, then warming and rising continues.

Finding the science in your world

Giant convection cycles are found in the oceans. These cycles are important in maintaining the Earth’s temperature balance and can influence global weather patterns.

Convection cycles also occur in the atmosphere, driving wind and clouds and affecting weather systems. Without convection cycles, Earth would not be shaped by rain, wind and even shifting continental plates and volcanoes.