While much needed rain showers have recently graced much of Iowa, most of this summer has been very dry. The lack of rainfall produces water availability stress in plants and their production of water vapor by transpiration is decreased. The result should show up in decreased air humidities as shown by the featured chart of Des Moines daily mean mixing ratio (the amount of water in the air versus total air). In general, this has been the case for most of the summer with humidity values running near or below long term average. The warm and humid weather we had in March is probably the most noticeable feature in this chart. The initial wet period we had to start May also shows up as an elevated period of higher humidities.

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Tags:   2012   mixingratio