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Desert Diary
Climate/Welcome Winter


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Today's the first day of winter, and aren't you looking forward to cooler weather? Oops—wrong desert! This is the Chihuahuan Desert, not South Africa's Kalahari. Well, now that I've sneakily gotten your attention, let's address how come it's the start of winter in the Kalahari and of summer around here.

We probably can blame it on a collision between the earth and another planet-sized body several billion years ago, the same collision that we think produced the moon. More to the point here, though, is that the axis of the earth was knocked askew. As a result, during part of our yearly journey around the sun, the northern hemisphere is tilted toward our star, and during part of the year it's tilted away. When our Chihuahuan Desert's sun is high in the southern skies, as it is now, the sun of the southern hemisphere's Kalahari Desert is low on the northern horizon. The more nearly direct summer sunlight supplies greater heat than the slanting rays of winter, easily explaining the reversed seasons of northern and southern hemispheres.
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Listen to the Audio (mp3 format) as recorded by KTEP, Public Radio for the Southwest.


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.