[AZ-Observing] 2014 Flagstaff nighttime cloudiness

  • From: Brian Skiff <bas@xxxxxxxxxx>
  • To: <az-observing@xxxxxxxxxxxxx>
  • Date: Thu, 1 Jan 2015 11:34:06 -0700

So how cloudy was it?  At least in Flagstaff, which I
consider to be representative of places in the Southwest,
it was a very typical year in astronomical terms
as far as nighttime cloudiness.
     June, unsurprisingly, was the clearest month
with 17 'photometric' nights (cloud-free dusk-to-dawn),
while July had just one, and December only two.  We ended
the year with 84 of those perfect nights, and another 69 nights
with at least 3 hours consecutive clear.  These added up to
1223 clear hours.  The averages from my 36-year record
are 93 +/- 18 photometric nights, and 1119 +/- 135 clear hours,
so last year was well within one standard deviation 
of "normal".
     The nightly details (almost every night since
June 1978) and annual summaries are posted at the
Lowell Web site:



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