IEM Daily Feature
Monday, 11 July 2022
Monday, 11 July 2022
Moisture Change
Posted: 11 Jul 2022 05:30 AM
Some call it corn sweat, others use fancier terms like evapotranspiration. The net effect is the same,
adding discomfort to summer time days in Iowa by increasing lower atmospheric humidity levels. The
featured chart is a bit of a deep dive into teasing out what the magnitude of this effect is. The grid
found on the chart presents a two dimensional histogram of daily change in specific humidity (mass
ratio of water vapor to air) between 10 AM and 9 PM. Positive values indicate an increase in moisture.
The lines present smoothed means for climatology, this year and the drought year of 2012. The annual
cycle is very clear and the impact of crop transpiration is readily apparent as well. The peak in mid July
is a sweet spot for corn activity and best frequencies of having ample available soil moisture. Crop
senescence typical by the first week of September nicely coincides with the climatology turning
negative as the drying effect of the fall season shows up until this start to become a wash later in
November.
Voting:
Good = 9
Bad = 1
Voting:
Good = 9
Bad = 1