Home LATEST NEWS No difference between dry cold and wet cold, according to science

No difference between dry cold and wet cold, according to science

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Air is made up of different gases, including nitrogen, oxygen, and carbon dioxide. It also contains amounts of water vapor that are constantly changing due to the water cycle.

Absolute humidity is the mass of water vapor in a specific volume of air, regardless of temperature.

Relative humidity is that shown in the daily weather forecast. It measures the concentration of water vapor in the air as a percentage of the maximum it could contain at a given temperature and pressure.

A woman cools off with a jet of water.

When it is hot, humidity plays an important role in how warm you feel outside.

Photo: TurnedNews.com / Ben Nelms

In summer, when we talk about relative humidity, a day of 30 ° C with 20% humidity will not feel the same way as a day with 90% humidity.

Damp heat can be unbearable, even dangerous. This is because the greater amount of water vapor present in hot air at high humidity levels can make it difficult to dissipate excess body heat through perspiration. Without this evaporation, you can get too hot very quickly.

The temperature makes a big difference

However, as the temperature drops, the relationship between water vapor and relative humidity changes.

When the air cools sufficiently and the relative humidity is 100%, there is condensation, the process by which vapor turns into liquid.

These water droplets are the clouds we see in the sky, and when the droplets are large and heavy enough, they fall as rain or snow.

So when the air cools, the relative humidity increases.

Therefore, a humidity of 90% at 25 ° C and a humidity of 90% at -10 ° C will be associated with different amounts of water.

At low temperatures, even at high relative humidities, there would be far fewer grams of water per kilogram of air.

So, in a Canadian winter, the amount of water in a humid cold is quite similar to that of a dry cold.

David Phillips, climatologist at Environment and Climate Change Canada, explains that in a kilogram of air at -20 ° C that is almost saturated, there will only be half a gram of extra water.

So there is very little difference, he said.

It is therefore clear that, if dry air is more pleasant than humid air, it cannot be due to humidity or water.

A quote from David Phillips, climatologist at Environment and Climate Change Canada

There are simply not enough water molecules in this air to conduct heat away from the body, so it is negligible., he adds.

This principle was put to the test and was the subject of a research article published in 1988 (New window) of Defense Research and Development Canada.

The paper looked at a number of experiments performed in the 1950s, where subjects were exposed in a laboratory environment to low temperatures at different levels of relative humidity.

Researchers [n’ont] not found a significant difference in physiological responses to high and low humidity levels , mentioned the report.

But why is the feeling different?

So, if this popular belief is a myth, why is a cold day on the East Coast so freezing while a -30 ° C day on the Prairies is more bearable?

It is other factors that come into play, not the humidity in the air. People’s individual tolerance and their ability to keep themselves dry also play a role.

This is why some people need to wear a toque at -2 ° C in the Maritimes, but these same people will not need to wear a toque in Edmonton until it is -10 ° C or -15. ° C.

The wind is also a game-changer. A -15 ° C day in Kingston, Ontario, with winds blowing at 50 kilometers per hour, will be just as cold as a calm day at -30 ° C in Edmonton or Regina.

The sunlight factor also comes into play. When humidity is high, there are often more clouds than during the cold, cloudless winter of the Prairies. The little rays of the sun warm us up a bit.

Another factor is clothing. Winter fashion on the Prairies tends to be a little different than in Toronto. Being wrapped up in a parka will obviously keep you warmer than much lighter clothes.

When it comes to clothing, however, David Phillips recalls that it is essential to stay dry to keep warm.

With information from Christy Climenhaga.

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