ILLINOIS — Regions blessed by large swaths of farmland can also be cursed with season spikes in humidity thanks to “corn sweat.”

You see, as corn and other crops grow, they give off moisture through their leaves. This happens throughout the growing season but reaches its peak as crops mature. Thanks to the US National Weather Service Central Illinois Facebook post, we know a bit more about the science behind this natural phenomenon.

The scientific term for the release of moisture is evapotranspiration. This is the combined process by which water is transferred from the land to the atmosphere through evaporation from soil and other surfaces, and transpiration from plants.

Full forecast details and more at the WGN Weather Center blog

For areas dominated by agriculture the total amount of water pumped into the atmosphere can be staggering. In Illinois, for instance, a mature corn crop can give off more than 35 billion gallons of water daily. This is enough water to fill more than 52,500 Olympic-size swimming pools.

As you might imagine, this amount of moisture added into the air has a direct impact on humidity levels and thus the heat index.

Why, though, do plants transpire, or “sweat,” at all? According to an article in the National Institutes of Health’s Library of Medicine, plant transpiration provides evaporative cooling for the leaf while also acting as the driving force to transport water and nutrients from its roots up into the rest of the plant.

For a scientific deep-dive on transpiration, we recommend this 2021 article posted by CID Bio-Science.