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Corn crops ramp up sticky, humid weather

A Minnesota researcher says much of the sticky, humid weather hovering over the state in the summer could be attributed to abundant corn crops.

University of Minnesota biometeorologist Tim Griffis has studied moisture in the air for more than a decade. He tells Minnesota Public Radio News that his research shows that more than 60 percent of local air moisture comes from fields of corn crops — and corn is likely the largest contributor.

“At this time of year, over corn, what we would see is evaporation rates that are about 40 to 50 percent higher than say over restored prairie or natural prairie,” Griffis said.

The National Weather Service in Des Moines, Iowa, seems to back that up. It recently said mature Iowa corn crops send 49 to 56 billion gallons of water into the atmosphere daily. That can force the dew point up as much as 10 degrees on a hot summer day.

Griffis collects data with sensitive air sampling devices that are in position for several years on a broadcast tower south of the metro area. The devices analyze water vapor — and can pinpoint whether individual droplets likely originated from crops, lakes or more distant sources. The equipment can’t detect exactly how much crops boost the dew point, though.

Other researchers are noting the same findings as the National Weather Service in Iowa.

“When you start looking at the large scale atmospheric processes over the entire corn belt region, it’s not unlikely that we might see 5-, maybe even 10-degree changes in dew point temperature over the corn-related areas versus the non-corn-related areas,” said University of Oklahoma meteorologist Jeffrey Basara.


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