Corn Sweat Is Real, and It’s Making the Heat Wave in the Midwest Even Worse

It may sound like a bad joke from the recesses of Reddit, but corn sweat is real. It refers to the moisture that corn and other crops release during periods of high temperatures. This moisture is then released into the air, making things a lot more humid—and even hotter for humans.

In fact, experts say that corn sweat is playing an important role in the heat wave in the Midwest, where 55 million people are under an extreme heat alerts.

Evapotranspiration. What is colloquially known as “corn sweat” has an official name: evapotranspiration. It refers to the process by which plants release water vapor into the air. As explained by AGDaily, plants absorb water from the soil through their roots for use in different metabolic and physiological processes. The plants go on to release the water as vapor through their stomata.

In short, it’s the plant version of breathing. And it's completely normal.

“The movement of water through this system is like a plant’s circulatory system,” Talon Becker, an agriculture educator at the University of Illinois Extension, told AGDaily. “It’s how they move nutrients and other mobile health things throughout the plant as well.”

Notably, evapotranspiration indicates that plants are healthy. When plants are stressed, they release less water as part of their defense mechanisms, which can also negatively affect their growth.

What does corn sweat have to do with the heat wave? While plants doing their thing may sound like something entirely separate from the heat wave, there’s a reason people are talking about corn sweat. It also has a name: dew point.

Specifically, the moisture the corn is releasing into the air is affecting the dew point. The dew point indicates the temperature the atmosphere would have to cool for water vapor to condense into droplets, according to the National Weather Service. The higher the dew point, the muggier it’s going to feel outside.

“The higher the dew point, the greater the amount of moisture in the air. This affects how ‘comfortable’ it will feel outside,” the agency explains. “When your body gets too hot, it begins to perspire or sweat to cool itself off. If the perspiration is not able to evaporate, the body cannot regulate its temperature.”

Corn sweat in Iowa. One of the most notable examples of corn sweat right now is in Iowa. In the state, corn releases between 49 to 56 billion gallons of water into the atmosphere every day, USA Today reported. Experts say this can add between 5 and 10 degrees Fahrenheit to the dew point.

Iowa’s not the only place full of corn, though. According to the Department of Agriculture, the U.S. is the largest producer, consumer, and exporter of corn worldwide. Farmers plant roughly 90 million acres of corn per year.

It's not the corn’s fault. Before you start blaming corn for your summer woes, you should know that it’s far from the only factor at play right now. Moisture from the Gulf of Mexico is also an important factor when it comes to Midwestern heat, as well as waterways and other plants, such as soybeans.

“The misconception might be that if there were no corn, then it wouldn’t happen,” Becker, the agriculture educator, said. “That’s just not true. All grasses and all plants are going to transpire.”

Nonetheless, the effect of corn sweat will disappear soon. Crops usually begin to emit less humidity in September, which is also when farmers start harvesting corn.

Image | Randall Wick

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