The 1930's Dust Bowl Drought

Dust Cloud
PhotoQuest/Archive Photos/Getty Images

The Dust Bowl was not only one of the worst droughts in United States history, but is generally thought of as the worst and most prolonged disaster in American history.

climatic events in the history of the United States was the "Dust Bowl" drought which devastated the United States central states region known as the Great Plains (High Plains). The Dust Bowl all but dried up an already depressed American economy in the 1930's creating millions of dollars in damages.

A Region Already Prone to Drought

The Plains region of the United States has a semi-arid, or steppe climate. The next driest to desert climates, semi-arid climates receive less than 20 inches (510 mm) of rainfall per year which makes drought a serious weather hazard. What's more, the Plains is positioned . High winds then generate dust storms.

broad expanse of flat land. air flows down the lee of the Rocky Mountains, warms and rushes out across the flat land = high winds

The Plains has episodic, recurrent drought: periods of average or above average rainfall alternate with periods of drought.

Known as the "Great American Desert" to early European and American explorers, the Great Plains was thought to be unsuitable for pioneer settlement and agriculture thanks to the lack of surface water. But an abnormal wet period during the would soon change all this. (And in .) As we'll soon see, a number of climatic events led to the disruption of this biome which led to the of the dust bowl.

"The Rain Follows the Plow"

wet weather in the 1920s

At this same time, the federal government was encouraging the development and settlement of the region for agriculture, which gave many a false impression of the lifestyle. This unusually wet period mistakenly led settlers and the government to believe that the region's climate had changed for the better, giving rise to the phrase "rain follows the plow." that plowing the land released moisture into the atmosphere, which, in turn, produced more rain.

Of course, unbeknownst to farmers at the time, this boom period relied on temporary climate conditions.

The Dry Summer of 1930

By the summer of 1930, those temporary climate conditions fell apart and once fertile farms began turning to dust. 

the influx of farmers and the lack of dryland farming was contributing to the of the Dust Bowl. The demand encouraged farmers to dramatically increase cultivation. But the agricultural methods favored by farmers -- mainly deep plowing -- eliminated the native grasses which held the soil in place and helped retain moisture during dry periods.

With modern technology, NASA now believes the Jet Stream was partly responsible for this drought.

Ocean Temperatures in the 1930's Were Unstable

Scientists at NASA's Goddard Space Flight Center recently used a computer model and satellite data to examine climate over the past century. In the study, cooler than normal tropical Pacific Ocean temperatures and warmer than normal tropical Atlantic Ocean temperatures created ideal drought conditions due to the unstable sea surface temperatures. The result was dry air and high temperatures in the Midwest from about 1931 to 1939.

The Normal Supply of Moist Air From the Gulf of Mexico Was Reduced.

Changes in sea surface temperatures create shifts in weather patterns. One way is by changing the patterns in the jet stream. In the 1930's, the jet stream was weakened causing the normally moisture rich air from the Gulf of Mexico to become drier. Low level winds further reduced the normal supply of moisture from the Gulf of Mexico and reduced rainfall throughout the US Midwest.

The Jet Stream Changed Course. The jet stream normally flows west over the Gulf of Mexico and turns northward pulling up moisture and dumping rain onto the Great Plains. As the jet stream weakened and changed course, it traveled farther south than normal starving the Midwest of precious rain.

Updated by Tiffany Means

 

References & Links

Dust, Drought, and Dreams Gone Dry. Urbana University

Siegfried Schubert, Max Suarez, Philip Pegion , Randal Koster, and Julio Bacmeister, "On the Cause of the 1930s Dust Bowl", March 19, 2004 SCIENCE Magazine.