The Thing about Humidity

As most of you know the coast of Liberia is one of the wettest places on Earth. During the wet season-- which has just begun-- it rains for days at a time without letup, and most of the year’s 200 plus inches of rain falls during the next four months. Coming from a moist Midwestern US area that sees 40 inches in a year, it’s an impressive display. But far more impressive than the rain is Liberia’s humidity, which is as high as it gets anywhere, just about 365 days of the year. For humans, and especially me, he thing about humidity is what is does to the body’s natural ability to cool itself. When we are hot, we sweat. Sweat has no cooling powers in itself. However it is designed to evaporate, and as it evaporates, the body cools. In dry climates, like Senegal closer to the Sahara, it is just as hot as in Liberia and often hotter. A person perspires there as much as here, but clothes are never wet and rarely does sweat collect on the brow. A person may not even realize he is sweating. The ultra dry air immediately takes it, resulting in a cooler body.

In Liberia, the air is so saturated with moisture that perspiration simply has no where to go—the body just gets wetter and wetter in a vain attempt to cool off. I go through about five shirts a day here if I’m not in the blessed air conditioning of car or work. At home, ten minutes of activity, like pounding a few nails or taking the generator out, immediately starts a process that drenches my shirt by the time I’m finished. Sweat, with no chance of evaporation, drips off my body or is continually being wrung out of the handkerchiefs I now carry everywhere. And my body just gets hotter.

It really is fascinating. I used to think the humidity caused me to sweat more, but this is not the case. The amazing humidity of Liberia simply cannot evaporate it, so it accumulates. I’ve never understood the mechanism of evaporative cooling until now, when it does not work.