Website Welcome Page Air is good at transferring thermal energy by CONVECTION

Definition:  Thermal CONVECTION is the transfer of thermal energy by the actual movement of heated material.

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Solids, liquids and gases are made of tiny pieces of matter called molecules. In gases these tiny pieces of matter are spaced far apart. This means we cannot see them directly though we can be aware of their presence in the effects of their movement in the wind. The challenge in teaching about Earth's climate is to make its invisible world of gases visible.

 The molecules in a gas are far apart because the bonds holding them together are weak. This means molecules can be moved with ease i.e. a small energy input results in large movement.

When gases are heated and expand they move upwards. Thermal CONVECTION is the name given to the transfer of thermal energy by the actual movement of heated molecules. It only occurs in liquids and gases.( By comparison, thermal CONDUCTION is the transfer that occurs when a warmed molecule touches a cooler molecule.)  

The ability of air molecules to move relatively freely gives the atmosphere its wonderful ability to transfer thermal energy around the planet and moderate its temperature extremes. We experience this thermal transfer as wind and rain.  

  Winds can move at over 300kmp and the water cycle can be measured in days.

Note: Thermal energy always moves from regions retaining higher amounts of thermal energy to regions with less. Transfer is one way.


A build-up of thermal energy in the atmosphere may lead to increased risk of weather ‘events’ such as droughts, floods and cyclones in some regions.


Note. Lava lamps provide a graphic illustration of convection. They are an excellent reminder to students of all ages of the process that drives the movement the plates of the earth, the currents of the oceans and the winds of the atmosphere.

This page is part of a programme  Communicating and Teaching the scientific principles underlying Climate Change issues.

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Increased Temperature= Increased Distance between Molecules.






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Global Air movement

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