I don't understand how convection ovens can cook food faster than radiant heat ovens. Guides to convection ovens claim that they cook food 25-30% faster than radiant heat ovens, but do not really explain the physics of it.
For example, let's say we have a big turkey. Now, we surround the turkey with air heated to 350F, that is convection cooking. The air transfers its heat by contact to the turkey.
In contrast, if we roast the turkey, we have a red-hot heating element at 1200F radiating the top of the turkey. To test this I put some chicken in the oven and right next to it a block of wood. Both were about 12 inches from the heating element. After some time, the surface of the chicken was 250F and the surface of the wood was 450F. I am not sure why there is a difference, or why having air at 350F would cook the chicken faster than the radiant method. If the top of the chicken is 250F, I would expect the diffusion of the heat from the top of the chicken to be more rapid than if it is convected by air, but I guess this must be wrong for some reason, but I don't know the reason.