Just deserts

A new weather text is the first to focus on Earth’s driest lands

by Bob Henson

Those who consider desert climates boring ought to try taking on a sandstorm at full blast. According to NCAR’s Tom Warner, the experience—torrid heat, howling wind, stinging grains of sand, and near-zero visibility—should make believers out of them. “The discomfort level and fear in a sandstorm are much greater than, for example, in a snow storm,” he says.

Warner has spent the past five years pulling together a unique book on the world’s driest climates. Desert Meteorology, to be published by Cambridge University Press this autumn, is both a textbook and a reference volume. As best Warner can tell, it’s the first book that incorporates the gamut of weather and climate in the world’s warm, arid lands. (Polar deserts are discussed only briefly.)

“There are a half-dozen different textbooks on tropical meteorology,” says Warner. Why have deserts, by comparison, gotten short shrift? “The expression ‘desert weather’ has a peculiar ring to midlatitude-centric meteorologists. I think there’s the perception that deserts aren’t important in any practical way and don’t have very interesting weather. They’re considered hot, dry, and boring.”

The facts say otherwise. Not only is there a vast variety of desert climates, Warner points out that, both as “barriers and attractions,” deserts have played a huge role in global society. “Most of the world’s early great civilizations developed at the margins of deserts,” he notes, “and virtually all of the world’s great contemporary religions were born in desert regions.”

While desert climate can be harsh, the crisp air and sunshine are luring people to urban centers from Phoenix to Cairo. More than 10% of the world’s six billion people now live in arid lands. This fraction will likely increase, says Warner, because most inhabitants of arid lands are in developing countries, where the rate of population growth is greatest. As he puts it, “Deserts are becoming less deserted.”

Warner’s own interest in deserts stemmed from years of work in NCAR’s Research Applications Program. He has helped lead forecast development projects for U.S. Army bases near White Sands, New Mexico; Yuma, Arizona; and Dugway, Utah. For this work, as well as for mesoscale modeling related to the 1991 and 2003 wars in Iraq, “I had to learn something about atmospheric processes and land-atmosphere interactions in the desert.” Warner started writing a journal review paper on these topics in 1998, and he says “it eventually grew out of all proportion to my original intentions. I could have kept it within bounds, but I just got engrossed in the subject.”

In searching the literature, Warner discovered that a great deal was already known about desert meteorology, but that knowledge was scattered across disciplines from soil physics to dryland vegetation. “There’s been a lot published on desertification, for example—you could fill a building with what’s been written on that. In other subjects, I had to dig.” The book includes desert-themed chapters on climate change, severe weather, bioclimatology, and optics, including scintillation and other factors that shape the extraordinary sunrises and sunsets observed over dry land.

The book also examines how specific deserts contrast with each other and how microclimates can vary within a specific desert. For example, Australia’s Sturt Desert includes shallow lakes, a swamp, both barren and lightly vegetated sand dunes, and a salt flat. Each subregion has a different mode of heat exchange between the surface and
the atmosphere.

This autumn Warner will test-drive the material he’s gathered by teaching a course on desert meteorology at the University of Colorado in Boulder. Although the subject has made its way into courses at other universities, Warner believes this will be the first college-level class completely devoted to desert weather.

Warner expects his book will find its greatest value as a reference for people not only in meteorology but in such fields as geography, botany, or environmental science. “They may not want to make a career out of studying this particular area, but they do work on problems that require some knowledge of atmospheric conditions in deserts. Right now they have no convenient place to go, because the literature is so scattered.”

 


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Is the 1990s decline in grad-school interest reversing?

Affairs of the atmosphere

The road to Doppler data

Geomagnetic storms may spur thermospheric vortices

Mammoth meeting bridges the world of geoscience

President’s Corner: Crossing the valleys of death and lost opportunities: Toward an Earth Information System

Web Watch

UCAR Community Calendar

Governance Update

Science Bit