Seattle , Washington , has a reputation for the kind of weather that would depress a duck . The picture above was taken on December 7 , 2015 , and though it depicts a saloon in Pioneer Square , it could ’ve just as well been describing Seattleites ' feelings about the conditions that daylight . That ’s because thanks to the recent attack of flooding rain , Monday , December 7 , 2015 , will go down as the darkest Clarence Shepard Day Jr. in Seattle in almost nine yr .
According to meteorologistScott Sistek at KOMO News , it was the darkest 24-hour interval recorded at the University of Washington in Seattle since December 14 , 2006 , and the secondly - drab day commemorate in the urban center in the twenty-first century .
According to American city stereotype , we should n’t be altogether surprised ; Seattle is seen as reliably gloomy and showery . That characterization is n’t always true , of course . But the metropolis has been inordinately cockeyed lately . And as good as we humans are at being able-bodied to judge how terribly gray and rainy it is , we can apply some hard science to objectively determine lugubriousness .
We use data collected by weather station every Clarence Day , whether it ’s check the temperature on our telephone set or hear to the weather forecast , which is partially compiled using current observations . There are G of these post around the world , measure temperature , dew tip ( moisture ) , confidential information data , and a fistful of other variables that tell us everything from soil moisture to melodic line pressure . One of the lesser - known sensor attached to many advanced weather condition post is called a pyranometer .
A pyranometer is a sensor that measures the amount of solar actinotherapy reaching the open ; high stratum of solar radiation mean that the airfoil is receiving bright , vivid temperateness , while low-down grade point sunlight that ’s block by swarm , trees , buildings , solar eclipse , alien spacecraft ( okay , maybe not those ) , or anything else that could potentially cast a shadow .
On a day with clear sky , bright sunshine , and no obstructions around the machine , the measurements recorded by a pyranometer plot on a chart will make a perfect bell curve , with level of solar radioactivity apace come up around dawning , peak with the sun ’s high compass point in the sky on that particular Clarence Day , then quickly waning until it drops to zero after sunset . The chart above shew a almost - thoroughgoing solar radiation graphon the campus of the University of South Alabamain Mobile , Alabama , on August 26 , 2015 . The usurious drop - off around 17:30 is the resultant role of the Dominicus dipping behind nearby Sir Herbert Beerbohm Tree an 60 minutes or two before sundown .
University of South Alabama
More often than not , though , these graphical record are jag , with sharp drops and spikes in radiation hap as clouds and other aim block out the sun , or their reflections magnify the sunlight . On a rainy day with thick swarm cover , very little solar radiation reach the ground , so the levels recorded are a small fraction of what you would see on a sunny day .
The below graph shows solar radiationrecorded at the University of Washingtonbetween midnight December 4 and midnight on December 8 . The tinier the stiletto heel on the graph , the drearier the day . According toweather legend Cliff Massat the University of Washington , on December 6 , Seattle had 2.56MJ / m2 ( megajoules per metre square — a unit used to measure solar radiation ) . Now take a look at that tiny little prominence on December 7 . It represent a mere 0.44 MJ / m2 . No marvel the day was so downhearted .
University of Washington
The combining of thick clouds , steady rain , Seattle ’s high latitude , and the sunshine ’s low angle ( we ’re just two week from the winter solstice ) created these conditions . The large rain in Seattle will continue for several more days — and it ’s a welcome mickle , since most of Washington and Oregonare still bog down in a drought . But the lack of sunshine is undoubtedly cheerless to some area resident .
