Why does humidity bother us more than heat?

You often hear that it's not so much the heat, but the humidity. This is a correct statement. But why does humidity bother us more than heat?

Sometimes we hear that it is not so much the heat that makes us suffer, but the humidity. An assertion as relevant as ever in the torrid days of summer.

But what scientific basis can we give to what now sounds like a catchphrase?

Why do they say that "humidity is worse than heat"

The answer comes from the National Weather Service of the National Oceanic and Atmospheric Administration (NOAA), an agency of the U.S. federal government responsible for providing warnings to citizens about adverse weather conditions for their protection and safety.

The NOAA explains that our sweat, to cool the body through the skin, must evaporate into the air through body heat. The air in fact can retain water and that is why, passing from the surface of our skin to the atmosphere, the function of sweating is realized, which consists in protecting us from excessive heat.

Naturally things change if we consider that the air can retain a not infinite amount of water. Therefore, once a certain threshold is exceeded, the sweat on our body cannot "make the jump" into the atmosphere.

In short, if the function of sweat is to cool our body by evaporating, this purpose is limited by an air already saturated with humidity, which cannot absorb much more water (not even that of our sweat). Sweat therefore remains on the surface of the skin. From a subjective point of view, the heat then becomes worse.

The consequences of this snag are of varying severity. They range from a sticky feeling, which makes walking outdoors less pleasant, to far more serious relapses, such as heat stroke, which also causes death, and which should be one of the reasons for taking action against climate change as soon as possible.

When humidity becomes very uncomfortable

High temperatures improve the air's ability to absorb, thus worsening the ability to regulate body temperature by sweat. According to NOAA, a temperature increase of only half a degree is equivalent to a 4% increase in water vapor in the atmosphere. This explains why humidity is more annoying in the summer than in the winter, even though the levels, perhaps, are identical.

What is the threshold of humidity to be considered "bearable"? There's no official number, but NOAA considers a relative humidity (RH) level of 50% or higher to be "very annoying".

Now that we've protected ourselves, we may want to protect our portable device from the heat. And so here's one to prevent notebooks and phones from overheating, as well as an explanation of why heat decreases smartphone battery life.

Giuseppe Giordano