But airflow is not the only reason for the sticky temperatures. Believe it or not this time of year, maturing corn in the fields can actually sweat and significantly increase in humidity. I’m sure you were likely taught about the hydrologic cycle in science class back in grade school. Well, moisture in the air not only comes from evaporation from lakes, rivers and oceans, but also occurs from plants in a process called evapotranspiration. Across the Midwest and here in the Ohio Valley this time of year we see lots and lots of corn - and yes - that corn can sweat, just like humans do. As air moves through the numerous fields of corn, that moisture is evaporated into the air.
According to the U.S. Geological Survey, during the growing season, just one acre of corn can sweat around 3,000 to 4,000 gallons of water per day. This moisture can add anywhere from 5 to 10 degrees to the dew point, which is a measure of moisture in the air. Dew point that is measured above 70 degrees is considered to be oppressive. Over the weekend, the dew point soared into the middle 70s to near 80 degrees from Iowa into Ohio. Yet, the dew point dropped off in areas that had less agricultural areas making it less humid.