How field crops impact our humidity levels

Crops do more than produce food. They can also impact our comfort!
As crops mature, they give off more and more moisture which increases humidity levels.
As crops mature, they give off more and more moisture which increases humidity levels.(WMTV)
Published: Jul. 25, 2020 at 9:32 PM CDT
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MADISON, Wis. (WMTV) -It’s hard to not notice the high humidity levels we have had through much of the month of July. In fact, it’s what combines with temperatures to create the dangerous heat index values at times. Of course, part of this is due to the pattern we are in and how it has been another wet year. The other part may surprise you and it has to do with the growing season. Specifically crops like corn.

AIR YOU CAN WEAR: Oppressive humidity levels sticking around through the day Sunday.

Posted by Meteorologist Brian Doogs NBC15 on Saturday, July 25, 2020

There are two processes that occur in every farm field. These are known as evaporation and evapotranspiration. Most people are familiar with evaporation, which involves moving water from the surface or soil into the atmosphere. It’s the same process that dries pavement after a rain event. You may not be as familiar with evapotranspiration, a process that moves water through a plant. Think of it as sweating, or as it’s sometimes called “corn sweat.”

Evaporation rates are closely tied to the amount of incoming solar radiation, which peaks during the summer months. Evapotranspiration rates are more dependent on crop maturity. As more water is taken from the soil for a plant to grow, the more moisture that will eventually be given off. Both processes do depend on consistent rainfall as a drought can leave little water to work with.

Evapotranspiration typically peaks in late July through early August, although it can vary from year to year depending on when the growing seasons starts and crops get in the field. In return, it becomes harder and harder to get cool dry air masses overhead as we push through the second half of summer. Those days will start to return as we enter fall and plants start to head into a harvest state.

If you’re looking for an experiment to do this summer, measuring evaporation is a rather simple process. Fill a couple of pans with water and take measurements several times during the day. With a few simple calculations, you can determine the evaporation rate for a day or week!

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