The heat goes on. We can expect another triple-digit day Thursday with sunny skies across western Nevada and the Sierra. A weak trough of low pressure breaks away from the northwest and will move close enough to us on Friday to give us a slight chance of an afternoon thunderstorm, but that should clear out over the weekend, bringing back sunny skies with highs dropping just slightly into the mid-90s.
So why does humid air feel warmer? First, let’s look at how your body cools itself. When the old bod feels more heat than it is comfortable with, the brain sends a message to the sweat glands to open up the taps and pour out a little water onto the skin. Richard Nixon’s brain was particularly adept at this. The water, of course, then evaporates. But before water can evaporate (turn from liquid to vapor), it must draw heat from somewhere in order to change its state (it’s called the heat of vaporization). Since it’s already in contact with your skin, it draws heat from your skin, your body cools down, and heat prostration is avoided. You can look at it as your body’s own swamp cooler, which is appropriate, since after a couple of days of sweating sans shower, you begin to feel and smell a bit swampy. (More tomorrow.)