When we get out of the water and are hit by a gust of wind we feel colder than we would if we were not wet. This happens because of two phenomena: the first is linked to the fact that the evaporation of water takes heat away from our skin (even without wind, in fact, just being wet makes us feel cooler); the second has to do with the so-called Wind Chill Effectthat is, the transfer of heat between our body and the air that touches us. When these two phenomena are added together, the heat loss is greater and faster.
Why Wind Makes Us Feel Cold: What Is the Wind Chill Effect and How Does It Work?
The Wind Chill is a index from the loss of body heat when we are exposed to the wind and it is essential in the winter months especially in Nordic countries with very cold climates. In fact, as happens with humidity, which makes us feel a higher temperature than what the thermometer indicates, the Wind Chill effect on the contrary It makes us perceive a lower external temperature. Wind Chill therefore causes the difference between the actual air temperature and the perceived (lower) temperature in windy conditions.
The effect depends on the air temperature (the lower it is, the greater the Wind Chill effect) and on the speed of the wind. The more the wind increases, the faster removes heat from our skin and lowers its temperature. It is the same process that occurs when we blow on a hot plate to cool it: the movement of the air in contact with the hot plate causes the food to cool more quickly.
The wind causes a transfer of body heat because it usually has a lower temperature than our body and will therefore tend to capture part of that heat. When we come into contact with a cold current we speak of heat dispersionthat is, a phenomenon that causes us to lose heat. In the case of the wind, this exchange occurs through a physical mechanism called convection: the air comes into contact with our skin, heats up and then tends to move away (warmer air is also lighter and tends to move upwards), replaced by cooler air. This continuous exchange of air in turn creates a small current of air on our skin and leads to losing heat much more quickly.
Evaporation of water
When we are wet, our body is covered in water droplets. We can compare these droplets to our sweat: in fact, they will naturally tend to evaporate but, as happens with sweat droplets, to do so they must absorb heat, specifically that emitted by our skin.
The energy that water needs to evaporate is called latent heat of evaporation and is removed from the body in the form of heatlowering the temperature of our skin and making us feel refreshed, just like what happens during thermoregulation with sweat.
On a wet body the effects are cumulative
If we are at the beach or in the pool on a windy day, the two effects will combine, taking more heat away from our body and making us feel colder!
The wind also favors and speeds up evaporation of water droplets, making us disperse more heat in less time compared to how much we would lose if we lay down on a sun lounger and sunbathed on a windless day.
