Ask Heather - why humidity affects us

KNOXVILLE, Tenn. (WVLT) -- We all know those humid days, you can't miss them, but a couple of people wanted to know why we have high humidity and why it has such an impact on us.

A couple of related questions here on the subject of humidity. Scott Atkins wanted to know what causes high humidity here, and Rick Blair wanted to know why it affects us.

Humidity, in general, refers to the amount of water vapor in the air. There are big circulations in the atmosphere and the ocean. The clockwise rotation in the deeper ocean currents leaves the right side cooler and the left side warmer. So, the West Coast of the U.S. is on the cooler side of the Pacific, leaving them with more mild temperatures. The left side of the Atlantic is the East Coast, leaving the Southeastern U.S. with warmer, moist air.

There are also shifts in air pressure that drive air masses, and causes fluctuations in temperature and moisture content of the air.

Here's why the higher humidity affects you ...

The body naturally cools itself through evaporation of the moisture on the skin. So you sweat, and it evaporates. But, if the air is warm, making you sweat, and it's humid, your sweat can't easily evaporate.

The inability for your body to naturally cool itself can be dangerous. For example, on the heat index chart, if it's 96 degrees and the Relative Humidity is 65%, it feels like 121 degrees! Note, this was designed for shade and a light breeze, so if you're in the direct sunlight it can actually feel up to 15 degrees hotter!

That can be dangerous and lead to heat related illnesses.

If you have a weather-related question, Ask Heather!

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