2 Heat Transfer-The movement of heat from a warmer object to a cooler object.
3 1. Conduction Heat transfer by direct contact of molecules. In other words, when one molecule runs into another and it runs into another, etc.It can occur in a solid, liquid or a gas.Occurs best in a solid because the molecules are close together.
5 2. ConvectionHeat transfer by means of up and down movements called convection currents.Can occur only in a liquid or a gas
6 Convection currents Heated molecules do 2 things: 1. they expand (move apart), become less dense and then..2. they rise.Cooled molecules do the exact opposite:1. they contract (get closer), become more dense and then…2. they sinkThat is what makes a hot air balloon rise.
7 3. RadiationHeat transfer through open space.Occurs in a gas only.