How ‘corn sweat’ is making a Midwest heat wave even worse

GREEN BAY, Wis. ( WFRV ) – Excessive heat warnings are in place across the Midwest Tuesday amid high temperatures and humidity, a combination made even worse by a phenomenon known as “corn sweat.”

Corn sweat makes the already humid Midwest summer feel even worse when the plant releases groundwater back into the atmosphere, University of Wisconsin Extension crops and soils outreach specialist Chris Clark told Nexstar’s WFRV .

“Corn sweat is called evapotranspiration or just transpiration,” explained Clark. “You can think about someone putting a clear garbage bag over that whole corn plant.”

Chris Clark further explained that one acre of corn can give off 3,000 to 4,000 gallons of “corn sweat,” which is water vapor that then enters back into the water cycle.

“The one acre to put into perspective is like a football field,” said Clark. “It is the plants reacting to that warmer weather, and so they also need more moisture, and so they’re up taking more from underground water and bringing that up to the atmosphere that we’re in.”

She said that in doing so, the corn stalk obtains the nutrients and uses them in photosynthesis to make sugars to put on a nice reproductive cob of corn.

This is an extremely normal process this time of year, especially during the hot and humid months.

“It does usually hit about this time of the year, in this August time frame, just because of the surrounding states and all of our local vegetation is at its fullest growth potential.”

Other corn-growing states, like Iowa and Illinois, add to the impact. Clark says the transpiration process is amplified by southerly winds, which bring in warmer temperatures and more moisture.

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