2008 Flagstaff Nighttime Cloudiness Summary


                 Jan  Feb  Mar  Apr  May  Jun  Jul  Aug  Sep  Oct  Nov  Dec  Yr
                              
                                        (nights)
           
Photometric        4    4   13   13    9   14    2    4    9   12    9
                                                           Monthly Average:  

Partial            4    7    7    5    5    2    1    1    5    5    2
                                                           Monthly Average:  

Spectroscopic      3    5    5    9    8    8    6    0    7    8    1
                                                           Monthly Average:  

Cloudy            20   13    6    3    9    6   22   26    9    6   18
                                                           Monthly Average: 

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Clear Hours       78   86  163  149   92  105   20   36  115  164  120
                                                           Monthly Average: 

Clear+Dark Hours  15   61   91   40   50   39   18    7   48   76   53
                                                           Monthly Average: 

Mean Consec      2.0  1.3  1.9  2.6  1.5  2.0  2.0  4.0  2.3  3.0  2.3
                                                           Monthly Average:  

Max Consec         3    2    5    5    3    4    2    4    4    4    4
                                                           Monthly Average:  
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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.