Convection

• Convection happens in liquids and gases.
• Heat energy causes the particles to gain energy and move quickly, causing the particles to collide and make them move further apart.
• This means there will be fewer particles in a fixed volume, so less dense - this less dense liquid or gas will rise and colder, more dense liquid or gas sinks = convection current
• The hotter air rises because it is less dense than cooler air, which then falls back down again.