The Weather Notebook: Drought No Doubt

Drought No Doubt
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Dave Thurlow, Host

Hi, I'm Dave Thurlow and this is The Weather Notebook. According to the dictionary, 'drought,' derived from the Old English word for dry, means 'lack of rain' -- but this definition fails to capture the terrible desolation of earth and atmosphere during prolonged periods without rainfall. 'The sky, absolutely cloudless, began to scare us with its light,' South Dakota author Hamlin Garland wrote of a decade-long drought during his boyhood in the 1880s.

Dust storm approaching Stratford, Texas. April 18, 1935.

Droughts occur when high pressure settles over a region and refuses to budge: the sinking motion of air causes compressional warming, which keeps clouds from forming and lowers relative humidity, thus removing the essential ingredients of rain. Droughts often come in cycles. Copious rain fell on the Great Plains during the 1870s, then ceased abruptly the following decade. Devastating drought parched the Southern Plains again in the 1930s, causing the notorious 'Dust Bowl.' Black blizzards composed of millions of tons of top soil boiled 8000 feet into the air, darkening the noon sky as far away as New York.

But worse may be on its way. A research team at NOAA's National Geophysical Data Center in Boulder, Colorado, reports that 20th century droughts, including the Dust Bowl, have been relatively moderate and short compared to the megadroughts of the 13th and 16th centuries. The NOAA researchers warn that similar drought conditions could recur in the future, leading to a natural disaster of a dimension unprecedented in the 20th century.

Climatologists still can't explain why droughts occur in some years -- or even decades -- and not in others. But there is no doubt that serious, and very possibly cataclysmic, drought will strike again.

Thanks to contributing writer David Laskin and for more information on droughts, visit our website, weathernotebook.org. Thanks to Subaru and the National Science Foundation.