Life used to be simpler. Forecasters told you the “relative humidity.” But, no. That’s no longer the best measure. Now it’s the “dew point.” Supposedly it tells how much total moisture’s in the air, which better correlates to mugginess. (You don’t feel muggy when it’s 100 percent humidity at 40 degrees. Supposedly. But I think you feel kind of clammy since you’re in a fog.) With me so far? If not, get my point? “Dew point” isn’t clear. It’s the temperature at which condensation will form. So? What’s that got to do with sweat? Too many mental steps. Much better would be to have a Muggy Index. Since a dew point of 55 is about the threshhold for mugginess, The Muggy Index is the dewpoint minus 55. So if the dew point’s 67, the Muggy Index is +12. Isn’t that more penetrable than fog?
For more on taking the mystery out of science and weather, see “Teaching True Science.”