Those of you around Ames may have noticed a brief period Monday morning with overcast skies. The automated weather station at the Ames airport has a sensor that attempts to estimate cloud coverage amounts at height. During this period, it was reporting overcast conditions at about eight thousand feet above ground level. The featured chart presents the frequency by week of the year that such overcast conditions are reported at a given height. This plot should be considered with a grain of salt as it is reproducing some intrinsic properties of the automated sensor at use rather than a climatology of cloud ceilings. For example, the sensor is limited to twelve thousand feet with nothing reported above that level. There are also some quirks with how overcast is reported above five thousand feet. So after all these quirks, does the plot have any value?!?! Well, yes as a nice annual signal is presented with a decrease in overcast conditions shown during the warm portion of the year. Increased heating and better deeper lower atmospheric mixing help to keep overcast conditions away from the near surface.

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Tags:   ceilings