Today's featured chart takes a look at roadway pavement temperatures based on the Iowa DOT RWIS station in Ames along Interstate 35. With peak insolation at hand, one may wonder if pavement temperatures also peak at this time? The featured chart indicates, that like soil and air temperatures, there is a bit of a thermal lag with the maximum temperatures observed during July. Indeed, pavement temperatures are supported by warming soils, so as the soils continue to warm with the summer season, less of the heating from the sun is lost to transfer into the soil below the pavement. If the relationship was this simple, perhaps some of the bumps in the annual curve need some more explanation. Two of the bumps in March and November are related to a processing quirk with this plot representing either noon standard or daylight time, so there's an artificial bump at those locations. What's happening during the end of August is not necessarily straight forward, but perhaps related to local soil types and perhaps the slope of the pavement surface to the sun or maybe even prevalent shadows at that hour.

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Tags:   pavement