A question we receive quite often at NBC6 is why we report on the heat index as much as, or even more than, we report on the temperature.
The heat index--also called the apparent temperature or feels-like temperature--is the temperature your body thinks it is when we have high humidity.
Our bodies have to work harder to keep cool during very humid days. When it is hot and dry outside (think: Phoenix or Las Vegas), we are sweating without ever feeling any sweat. That's because as quickly as the sweat condenses onto our skin, it evaporates. That keeps us cool because evaporation is a cooling process.
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When it's humid out, we sweat a lot in Florida. The sweat is condensing onto our skin more quickly than it is evaporating because the air is saturated with humidity. That means we have to work harder to stay cool and the actual temperature becomes insignificant.
It is the humidity that gives us the feels-like temperature, a number much more relevant and one that tells us if we are in danger.
Just think, if there were no humidity, we could open the windows at night in the middle of the summer if it were 80 degrees. But we usually can't, because the humidity makes it feel much warmer.
As far as climate change, there is actually a connection.
For every 1 degree rise in the temperature, there is a 4 percent rise in available moisture. That means more rain, but also more humidity and a higher heat index.
That is why we have had so many heat advisories this summer. Those alerts are based on the heat index, not the actual temperature.
And for folks living up north in the winter, the wind chill is also the feels-like temperature, but in that case, it tells us how long we can be outside before we damage our skin when you combine the effects of temperature and wind.
