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Desert Diary


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What a shock it can be. Visiting places outside of our desert Southwest, that is. Most of us, in the desert, can be quite comfortable outside as temperatures approach 100 as long as we're protected against the summertime sun. But step off a plane in Houston or Miami at those temperatures? Ah! That's something else again.

And what's the difference? Humidity, of course! Surely you've all heard that "It's not the heat, it's the humidity," a folk saying that, for once, gets it right. But what is humidity, and why does it change a comfortable temperature to unbearably hot? Simply put, humidity is the amount of water in the air compared to the amount the air COULD hold. In the desert, there's so little water available that the air almost always can hold a lot more, but in summertime Houston, the air tends to be saturated—practically dripping! So why the difference in comfort? We cool our bodies largely by evaporation of sweat, perspiration that evaporates readily in the desert but has no place to go in air already filled to capacity.
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Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.

Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.