Convection:Heat convection is the transfer of heat from one place to another by the movement of fluids such as air or vapour gas. It is also a contactless method to transfer heat as well.

solder reflow oven The modern solder reflow oven use the concepts of radiation and convection combined. Heat is emitted by ceramic heat element with infrared radiation, but it doesn't deliver it to a PCB directly. The heat will transfer to a heat regulator first to make heat output even. A convection fan will blow the hot air to an inner chamber. The target PCB will get heat consistency in any spot.