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Decorah Wins

21 May 2020 02:22 AM
Typically being located in the far northeastern corner of Iowa means you experience some of the cooler temperatures within the state. Wednesday was an exception to that generality with Decorah (site id: DEH) reporting the warmest high temperature near 72 degrees. The reason why Decorah was the warmest was the location actually saw significant sunshine whereas the most of the rest of the state was cloudy. The featured chart compares an IEM produced solar radiation estimate based on HRRR model data against the reported high temperature for airport weather stations in the state. Selected sites are labeled by their station identifier. The relationship between the two variables is clear with increasing sunshine leading to warmer temperatures.

Voting:
Good: 10
Bad: 0

Tags:   solar   radiation  

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Daylight Duration and Change

10 Jan 2014 05:37 AM
While the days recently have been noticeably cold, they have almost been noticeably getting longer! Daylight time increase after the winter solstice (21 Dec) until the summer solstice on 21 June. The top panel in the featured chart presents the daylight time by day of year and the bottom chart presents the day to day change in daylight time. Three locations are shown to illustrate the difference with latitude. For daylight duration, the three lines intersect on the vernal and autumnal equinox as all locations on earth are at approximately 12 hours of daylight. For the daily change plot, the three lines intersect at the solstice as the rate changes sign for all locations on earth. It is kind of interesting to note how the daily change curve flattens out for Anchorage. The hand-waving explanation is that this is due to the trigonometry involved with the cosine function rate of change flattening.

Voting:
Good: 83
Bad: 11
Abstain: 9

Tags:   solar  

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Less Daylight Time

21 Jun 2013 05:42 AM
It is somewhat ironic that the first day of summer also is the first day with shortening daylight time. The featured map shows the idealized change in daylight time from Friday to Saturday. Iowa will loose just over four seconds! Of course, this change accelerates as the summer moves along. The start of the summer season will also feature some of the hottest and muggiest weather we have seen so far.

Voting:
Good: 114
Bad: 24

Tags:   solar