High Humidity and the Growing Corn Crop - How Those Two Can Be Related

When we think of high humidity we don't typically think of corn.  But corn in the heart of summer actually has some contribution to the higher humidity we typically feel during July and early August.  It's through a process called - Evapotranspiration.  Huh?!?  You may think that is just a word I made up, but it's true.  As the corn continues to grow during the summer, moisture evaporates off of the corn leaves into the atmosphere.  The word 'Evapotranspiration' is really a combination of two words: Evaporation and Transpiration.  We know what evaporation means, but we might not exactly know what transpiration means.  Transpiration is basically evaporation of water from plant leaves. 

The corn stalk draws up moisture from the soil and some of that moisture is able to escape back into the atmosphere through the corn leaf.  The warmer the surrounding air, the more moisture it can hold from the corn leaf (assuming the corn stalk has ample soil moisture).  Some scientists have even noted an increase in dew point temperatures across the Corn Belt over the past several years.  Corn in those areas being grown in more dense fields could be a contributing factor, but it's also important to note that high dew point temperatures can also be caused by other weather related factors - such as a very recent heavy rain event.  Crop evapotranspiration (ET) typically peaks in July and August and begins to decrease towards the beginning of fall as the crop is getting close to harvest.