Why 34 degrees Celsius air temperature feels so hot at 37 degrees Celsius body temperature

It seems counterintuitive: why do we feel uncomfortably hot when the air temperature is 34 degrees Celsius, even though our internal body temperature hovers around 37 degrees Celsius? Andreas Rössler, a physiologist at the Medical University of Graz, explains this apparent paradox.

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The body has not the same temperature everywhere. The 37 degrees is the body core temperature. It must be maintained within a fairly narrow range so that important biochemical processes can take place.

The human body must maintain a core temperature of approximately 37 degrees Celsius for essential biochemical processes like breathing and digestion to function. These processes generate heat, which the body must dissipate to the surrounding environment. This heat exchange works efficiently only when the environment is cooler than the body.

However, air is an inefficient conductor of heat. When the outside temperature climbs above 30 degrees Celsius, the body struggles to release its internally generated heat. To compensate, the body initiates sweating, a process that cools the skin as the sweat evaporates.

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Air is, however, a poor conductor of heat.

Water, in contrast, is a much better conductor of heat. This is why a 30-degree Celsius water temperature can feel pleasant, and why swimming pools offer effective cooling. Conversely, dry heat in a sauna can be tolerable until the addition of water, which dramatically increases heat transfer. Individual perception of heat also varies, influenced by the distribution of heat and cold receptors across the body.

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Everyone has heat and cold receptors, which are distributed differently on the body.