Page 71 - Barbecue Chicken Made Easy

Conduction is the most concentrated energy and a basic example is food in contact with hot metal. Conduction from hot metal is what creates grill marks on the food.
Infrared radiation (IR) usually comes from flame or glowing embers directly below the food. This concentrated form of energy packs a wallop and helps sear foods and get dark crusts in a hurry.
Convection airflow is relatively gentle warm air circulating inside the grill, especially when the lid is down.
It is important to think of these as energy rather than temperature. As an example, turn your indoor oven to 200°F and stick your arm in there. You can do this. It won’t burn your hair off. Now touch the metal grates. When you get back from the hospital you will understand that, although the air and the racks were both 200°F they held and delivered different levels of energy.
Infrared is altogether different. Stand under a tree on a sunny 90°F day. Sweaty hot, but the shade protects you from the ultraviolet radiation (UV). Now step into the sun. It burns! Although UV and IR are different wavelengths, they are both forms of radiation. When you place food directly above hot coals or gas flames, you are subjecting it to IR. It is like putting it in the sun. You can put a thermometer there but it is misleading because IR is best measured in calories, not degrees of temperature. We refer to IR as Warp 10, a dumb Star Trek reference.
Then there is smoke, which we think of as a spice or flavoring element. Some of it comes from charcoal (gas has no flavor), but when charcoal is fully engaged it doesn’t produce a lot of smoke. Some of it comes from vaporized drippings of juices, fat, and spices. But the most flavor comes from burning wood. We’ll discuss this in more detail below.