[vsnet-chat 3918] Flagstaff nighttime cloudiness 2000

[Brian Skiff <bas@lowell.edu>]

     We had a relatively poor year as far as nighttime cloudiness and total
clear hours goes:  75 nights and 868 clear hours.  The annual averages since
1979 are 94 (+/-22) fully photometric nights and 1082 (+/-137) clear hours by
my rather conservative definitions.  We got only one stretch of as many as five
consecutive clear nights.

\Brian

===============================================================================

2000 Flagstaff Nighttime Cloudiness Summary


                 Jan  Feb  Mar  Apr  May  Jun  Jul  Aug  Sep  Oct  Nov  Dec  Yr
                              
                                        (nights)
           
Photometric        2    1    5    9   10   11    7    1   10   10    7    2   75
                                                           Monthly Average:  6.3

Partial            6    4    4    4    5    0    1    2    8    3    6    5   48
                                                           Monthly Average:  4.0

Spectroscopic      5    2    6   10    7    6    8    3    6    2    4   10   69
                                                           Monthly Average:  5.8

Cloudy            18   22   16    7    9   13   15   25    6   16   13   14  174
                                                           Monthly Average: 14.5

-------------------------------------------------------------------------------

Clear Hours       64   26   78  105   89   63   54   18  139  120  112   59  868
                                                           Monthly Average: 72.3

Clear+Dark Hours  62   15   40   73   59   34   21    2   68   49   41   41  505
                                                           Monthly Average: 42.1

Mean Consec      1.0  1.0  1.7  1.5  2.0  3.7  3.5  1.0  1.4  1.7  1.8  1.0
                                                           Monthly Average:  1.8

Max Consec         1    1    2    2    3    5    4    1    3    3    2    1
                                                           Monthly Average:  2.3
-------------------------------------------------------------------------------

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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