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What exactly is humidity and how does it affect our daily lives?

Woman drinking water in hot sun : Photo © nicolas hansen/Getty Images Photo

Humidity is a constant and important factor in our lives. It is simply a result of the fact that water exists at varying rates in the gas phase (known as water vapor) in our atmosphere. Without water vapor in the atmosphere, the Earth's surface temperature would be much cooler (water vapor is the most important greenhouse gas), so we're all thankful for that. However, high humidity can be exceedingly uncomfortable.

Here are a few explanations for moments in our daily lives when high humidity is quite noticeable.


Sweat may be unpleasant, but it's doing an important job: helping your overheated body cool off by evaporating into the air and converting sensible heat into latent heat. When the air is close to being saturated with water vapor, sweat evaporates at a lower rate, reducing its cooling properties and keeping your body temperature high. At times, the impact can be more severe than just feeling a little overheated. When the body directs blood to its surface in an attempt to cool off, it is diverted from the brain and internal organs, which can result in heat exhaustion or heatstroke.


The hair care industry must be grateful to high humidity for making anti-frizz products a necessity. But what exactly is it that makes hair curl, wave or frizz when it's humid? Keratin proteins in hair are sensitive to the amount of hydrogen in the air. When humidity is high, the number of hydrogen molecules in the air increases (water, after all, has two hydrogen atoms for each molecule) and temporary hydrogen bonds form between the proteins, resulting in an interesting change in hairstyle.


Nothing's better than throwing a grill party on a sultry summer day — except when the radio shorts out. Humidity can limit the effect of insulation and the effectiveness of transistors within electronic devices. If you brought that radio outside from a cool, dry location, condensation may form on its circuit boards when the air around the circuit boards warms up past the dew point temperature. That would cut off your favorite song before it even hits the chorus.


Are you coming or going? Either way, humidity may thwart you. When it's humid, excess moisture can be absorbed by wooden doors, causing the wood to expand and warp slightly, which makes them stick when you try to open or close them. To remedy this, try adjusting the joints or sanding off some of the wood.


For those who suffer from disorders such as asthma or chronic obstructive pulmonary disease (COPD), the extra work done by the body to maintain a normal temperature, despite high heat and humidity, can result in breathing issues. One of the reasons for this is that in any given volume of air, sometimes a higher concentration of water vapor can mean a decreased concentration of any of the other usual gases that make up the air, which includes oxygen. The increased moisture in the air can also promote the growth of mold and dust mites, which are known to cause asthma attacks.

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