[AZ-Observing] Flagstaff 2004 nighttime cloudiness
- From: Brian Skiff <Brian.Skiff@xxxxxxxxxx>
- To: az-observing@xxxxxxxxxxxxx
- Date: Fri, 31 Dec 2004 21:51:45 -0700 (MST)
We had a pretty good year in Flagstaff as far as observing weather goes.
The total number of completely cloudfree nights, 102, was typical, but the
number of clear _hours_, about 1200 by my reckoning, was above average at
the +1-sigma level.
I started keeping this record of the nighttime cloudiness in June 1978,
so this marks the twenty-sixth full year for which I have results. In 18 of
the 26 years, May or June was our best month (or one or them), with around
15 clear nights.
\Brian
===============================================================================
2004 Flagstaff Nighttime Cloudiness Summary
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Yr
(nights)
Photometric 5 6 7 10 14 12 5 7 11 8 6 11 102
Monthly Average: 8.5
Partial 7 3 5 2 4 3 1 5 5 3 0 4 42
Monthly Average: 3.5
Spectroscopic 3 1 6 5 5 11 6 0 0 4 3 3 47
Monthly Average: 3.9
Cloudy 16 19 13 13 18 4 19 19 14 16 21 13 185
Monthly Average: 15.4
-------------------------------------------------------------------------------
Clear Hours 91 86 100 102 129 96 39 83 127 100 68 162 1183
Monthly Average: 98.6
Clear+Dark Hours 38 27 49 72 53 61 1 27 62 49 27 85 551
Monthly Average: 45.9
Mean Consec 1.0 1.5 2.3 2.5 2.3 2.4 1.7 1.8 2.8 1.6 2.3 2.2
Monthly Average: 2.0
Max Consec 1 3 3 5 5 4 2 4 4 3 3 3
Monthly Average: 3.3
-------------------------------------------------------------------------------
Definitions:
Photometric - cloudfree dusk-to-dawn.
Partial - at least 3 consecutive cloudfree hours during the night.
Spectroscopic - less than about 1 mag. extinction throughout the night.
Cloudy - cloudy.
Clear+Dark Hours = photometric hours with moon absent.
Mean Consec = mean number of consecutive photometric nights during the month.
Max Consec = maximum number of consecutive photometric nights during the month.
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