Re: [Phys-L] Percent of Sun Covered Duing Eclipse
I think people forget just how bright sunlight is (and how adaptable our
eyes and brains are).
The illumination from the sun is up to ~ 100,000 lux. A cloudy day is
around ~ 1,000 lux and typical office lighting is even less. So even 90%
coverage of the sun is STILL brighter than an overcast day. Given the slow
change in brightness, it is not at all surprising that the effect is not
dramatic (until you go from 99% to 100% coverage).
https://en.wikipedia.org/wiki/Lux
On Tue, Apr 9, 2024 at 9:22 AM Richard Tarara via Phys-l <
phys-l@mail.phys-l.org> wrote:
> We were supposedly to be in the higher 90s percent-wise but saw the
> same---some darkening but nothing very spectacular. Unfortunately, I
> didn't
> have the proper glasses and my pin-hole camera attempt didn't work too well
> either.
>
> Richard W. Tarara
> Professor of Physics, emeritus
> Saint Mary's College
> Notre Dame, Indiana
>
> Free Physics Instructional Software
> Windows and Mac
> sites.saintmarys.edu/~rtarara/software.html
>
> -----Original Message-----
> From: Phys-l <phys-l-bounces@mail.phys-l.org> On Behalf Of dgpolvani---
> via
> Phys-l
> Sent: Monday, April 8, 2024 6:14 PM
> To: Phys-L@Phys-L.org
> Cc: dgpolvani@gmail.com
> Subject: [Phys-L] Percent of Sun Covered Duing Eclipse
>
> Here in Baltimore one of the weather stations announced our partial eclipse
> would be 88% at maximum (3:02 pm EDT). At this time, the sky did grow
> darker, but not as dark as I expected given an 88% eclipse. Was the
> weather
> report wrong, or is the amount of sunlight received by a spot on the earth
> not directly proportional to the amount of the sun's disk visible at that
> spot? I am ignoring secondary effects such as the sun's corona.
>
> Don Polvani retired physicist, engineer
>
>
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