Convection

The cool particles gain kinetic energy when they are heated from the source and expands as it heats up. The particles become less dense than the surrounding cold air therefore it rises and displace the cool air. Cool particles are more dense therefore they fall and move towards the heat source to take the place of the warm particles. They then heat up and rise while other particles cool down and fall.

Example of convection:

- in fridges to cool it down.
Heat is carried away, therefore the back of fridges are always warm.

- Land & sea breezes are due to convection.
- Atmospheric winds.
- Hot water systems.