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Crazy Convection
‘Convection’ is a word used to describe the way heat moves in a fluid or a gas by the movement of the substance. Supplying heat energy to a liquid or gas causes the atoms to have more energy making them expand. This, in turn, makes the heated area more spread out than the surroundings, causing it to rise.
As it rises, it begins to cool down. This means it now has less energy, so becomes denser (more closely packed) and begins to fall to the bottom one more. This process continues in a cycle that scientists call convection. Convection can occur in both liquids and solids where atoms and molecules have some freedom to move.
Convection plays a huge role in our environment around us. The ocean and weather systems are ruled by powerful convection currents in both the air and the sea, which give us the tides, clouds, winds and rain. Earthquakes and volcanoes are caused by massive convection currents in the molten magma under the Earth’s crust, which actually move the surface of the Earth back and forth with their immense force!
Convection can also be found in the home. Your central heating systems and ovens use convection to spread heat quickly and evenly around a space. On an even larger scale, massive convection currents circulate heat inside stars, including our own Sun, and are the causes of Sunspots and solar flares.
In order to demonstrate the fascinating process of thermal convection, a green dye has been added to this beaker of water (which sinks to the bottom). When the beaker is heated from below, the dye expands and rises, starting off these beautiful convection currents!
Some good web links to try:
