LANSING, Mich. (WLNS) — When combining heat and humidity, we get a concept called the heat index.

But how does the heat index work, and why does it exist?

Imagine the actual air temperature outside is right around 94 degrees, with a dew point temperature in the low 50s. It’s still comfortable outside, and that is because the moisture or sweat that builds up on your skin can evaporate into the atmosphere, thus giving you a cooling sensation.

The moist air buildup process is known as evaporative cooling.

Let’s crank up our dew point temperature to around 74 degrees, now in these conditions we have a heat index of 104 degrees outside.

So now, it’s not only hot but downright uncomfortable.

But what’s the difference?

The dew point temperatures.

When we have a dew point temperature in the 70s, your body just keeps sweating and sweating, but we have less evaporative cooling occurring, that moisture has nowhere to go so it just continues to build up on your skin.

Want to learn more? Watch the video in the player above.