Low Solar Radiation: Is That Why You are Depressed?

I can't tell you how many folks have emailed me or complained in person about what they perceive as a sudden turn to darkness.  They feel depressed, tired and anxious.  Daytime light helps maintain our circadian rhythms and a number of people suffer from Seasonal Affective Disorder (SAD) when the days grow short and clouds fill the sky.

So what is the truth?  How bad has it gotten?  Let's check. 

Here is the solar radiation reaching the surface in Seattle from the wonderful WSU AgWeaherNet collection of stations over the past six months (check below).   During June and July, some days had nearly 30 MegaJoules per square meter (a Joule is a unit of energy), and even cloudy days had about 15.  But recently, we have had days with 3-4 MegaJoules....way, way lower.   And the last few days, had no real spike upward in radiation to provide relief. 

Folks are right...it HAS been dark.   Part of the problem is, of course, the turn towards more clouds the last few weeks.   But, in addition, the number of hours of daylight has progressively dropped, something shown by the figure below (the vertical white line indicates today).   We have rapidly lost daytime hours the past few months and we are close to hitting bottom.

The recent switch to daylight savings time makes it even worse, with our commute home now in darkness.

The air even feels different, with biting cool, dampness that Seattle residents fear.   Here is the plot of relative humidity for the past 6 months at Seattle.  During the past month, relative humidity has jumped to around 80-90%, resulting in not only a feeling of dampness, but a loss of visibility due to fog and water-absorptive particles in the atmosphere.

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Very dark, clouds, humid, and cool---enough to scare off many Californians, and certainly able to explain the down feelings some folks have experienced during the past week.

from Cliff Mass Weather and Climate Blog http://ift.tt/2AQwHaT