Sunlight? Gray!

Month may become dimmest on record --- this headline leaped from the font page of this morning's Boston Globe. Somehow I usually think that I am imagining that the weather is gray and unseasonable, cool and wet, day after day after day. Apparently it isn't my imagination this time!

I was fascinated with the description of the device that is used to register sunlight at the Blue Hills Meterological Observatory:

"...the primitive, softball-sized glass sphere on the observatory’s roof, a device that has burned lines on paper since 1885 to record nearly every burst of sunshine strong enough to cast a faint shadow."

According to the article, the sun has been obscured by clouds this month more than any other June on record since 1903, and there is still a possibility that a new record could be set.

Interested? Read the Boston Globe article, Month may become dimmest on record.

I found the diagram of the instrument used even more interesting than the article. Click to see how a pyroheliometer measures sunshine.