The feeling of 34 degrees in the shade can be trying for the body, while 34 degrees in water are often perceived as pleasant. Scientific journalist Daniel Theis of SRF explains why.
Why do we find hot water more pleasant than hot air?
At first glance, it does not seem logical. However, our body constantly produces heat – we are like small radiators that work permanently. In a small room with closed windows, if ten or twenty people are present, it is quickly warmer.
To prevent our bodies from overheating, we must constantly evacuate heat. And we are surprisingly sensitive: a body temperature of around 37 degrees is ideal, but from around 38 degrees, it becomes unpleasant. If the heat exchange does not work well, therefore our body can quickly be too hot.
Why does it work differently in water and air?
Water can absorb and evacuate body heat much more effectively than air. We can compare this with solid materials: when we touch a metal at 20 degrees, it seems rather fresh because it quickly extracts the heat from our hand. Wood at the same temperature seems pleasant because it leads the heat less well. This difference also explains our perception of temperature in water and air.
As water transports heat much more effectively, we can have higher temperatures without feeling overheating. However, when it is as hot as they are in Switzerland, it is not highly recommended to immerse yourself in too hot water. It is best to take a lukewarm shower rather than a full 34 -degree bath.
What is the thermoneutrality area?
There is a so -called thermoneutrality area, which could also be called “comfort zone”. In this temperature range, the body needs neither to produce additional heat, nor to evacuate an excess heat. In the water, this area is around 33 to 34 degrees Celsius – this is where we find it pleasant, neither too hot nor too cold.
In the air, this area is much lower. If we do not wear clothes and we do not move, it is about 27 degrees. Factors such as clothing, physical activity or wind can of course significantly modify this value.
What role does air humidity play?
Air humidity strongly influences our perception of temperature. At 27 degrees with dry air, many people feel good, but 27 degrees with wet air, it can quickly become unpleasant. The reason: in a damp air, sweat on the skin evaporates badly, if at all. However, this evaporation is crucial so that our body can evacuate excess heat. When this cooling mechanism is hampered, heat accumulates and the feeling of heat increases considerably.
Ranja Kamal (SRF)