The science behind humidity and why it makes us feel hotter

KALAMAZOO, Mich. (WWMT) – Summer may not officially begin until the solstice on Tuesday, June 21, but that hasn't stopped Mother Nature from sweating out some high temperatures across the U.S.

High humidity levels, exacerbating that summer-like heat, makes temperatures feel even hotter. It's all tied to this charming biological process called sweating.

The human body wants to stay in a constant state of comfortability, which is an internal temperature of about 98.6 degrees.

That internal temperature, though, can adjust based on the external temperature.Cold days may cause it to fall, while hot days may cause it to rise.

Our bodies, always striving for that happy 98.6, respond almost immediately by either shivering or sweating. The rapid muscle contractions triggered by shivering generate heat by expending energy, helping to warm the body up.

On the other hand, the evaporation of water triggered by sweating steals heat away from the body, working to cool it down. This process, known as evaporational cooling, leaves a salty film behind on the skin, often realized by runners after a hard workout.

While the human body may activate these natural defenses against Mother Nature, it meets its match once humidity enters the weather ring. That's because humidity, or the measurement of moisture in the air, prevents sweat from evaporating.

The air simply can't hold anymore water, so sweat "sticks" to the skin, making a person feeling even hotter.

This apparent temperature is known as the heat index, or what temperature it actually feels like outside. The mathematical road to figuring out this number is a long andcomplicatedone, but fortunately, the National Weather Service created a short-cut.

Thisonline calculatoronly calls for the temperature and dew point temperature to solve forthe heat index. The general rule of thumb being the higher the dew point, the higher the heat index.