Conduction, Convection, and Radiation

Heat transfer refers to how heat energy moves from one point to another, whether on Earth, in the atmosphere, or in space. There are three main types of heat transfer: conduction, convection, and radiation.

Conduction is the transfer of heat through molecular contact. An example is a metal spoon heating up when held over a flame; the energy from the flame causes molecules to vibrate and transfer energy throughout the spoon. Conduction is most effective in solid materials.

Convection is heat transfer due to density differences. When air near a flame heats up, it expands, becomes less dense, and rises, carrying heat energy upwards. This process is most effective in liquids and gases.

Radiation is heat transfer by wave motion, specifically electromagnetic waves. Heat from a flame not only rises (convection) but also travels outwards in waves. Radiation does not require a material medium to travel, which is how energy from the sun reaches Earth.

The three types of heat transfer are conduction (contact), convection (density differences), and radiation (waves). A campfire provides a good illustration of all three: conduction heats a pot placed over the flame, convection causes heat to rise, and radiation emits heat outwards in waves.