Heat Transfer

Heat moves by conduction (contact with a surface), convection (moving air or water), radiation (sunlight and warm surroundings) and evaporation (sweat drying). Every cooling method you use is one or more of these channels working in your favor.

Each channel has limits. Evaporation slows when the air is humid. Convection can add heat when the air is hotter than your skin. Conduction needs a meaningful temperature difference and good contact. Radiation from direct sun can add a large load even in moderate air temperatures.

This is why a single number like air temperature never tells the whole story, and why combining methods, such as shade plus airflow plus a cool surface to hold, usually works better than relying on one.