MAINE, USA — It took awhile to get here but we're finally talking about the heat! It's getting hot, and it's getting humid, which will make everything feel even hotter...but why?
It all has to do with evaporation.
When water evaporates, it transforms from a liquid to a gas. Energy (in the form of heat) is required to make this transformation.
Our bodies are doing the same thing when we sweat.
As temperatures increase, our bodies sweat in order to cool us off. To evaporate the sweat, heat energy is taken from our skin and put into the liquid sweat to turn it into a gas. The loss of that heat energy cools us off.
On a less humid day, there is a lot of space present in the air to accept more water vapor. This means that sweat can easily evaporate and cool us off.
If the day is very humid, the air is more filled with water vapor and can't take it as easily. This makes it more difficult for sweat to evaporate, which means we can't get rid of that heat energy, and we feel hotter.
Heat index temperatures are also known as "feels like" temperatures. While the temperatures may peak in the low 80s, we feel even hotter due to the humidity and lack of sweat evaporation.
This lowers our comfort index. As humans, we want the perfect conditions to be comfortable: not too hot, not too cold, not too dry, but also not too humid. This week is going to trend to be hot during the days, cooler overnight, and humid the entire time.