1992 Flagstaff Nighttime Cloudiness Summary Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Yr (nights) Photometric 8 5 3 3 2 15 5 2 13 11 12 3 82 Monthly Average: 6.8 Partial 6 1 7 5 2 6 3 3 6 3 4 9 55 Monthly Average: 4.6 Spectroscopic 8 0 2 11 3 0 5 0 10 7 4 2 52 Monthly Average: 4.3 Cloudy 9 23 19 11 24 9 18 26 1 10 10 17 177 Monthly Average: 14.8 -------------------------------------------------------------------------------- Clear Hours 146 60 60 50 22 128 44 31 146 127 141 81 1036 Monthly Average: 86.3 Clear+Dark Hours 78 40 17 33 2 61 20 26 80 34 77 49 517 Monthly Average: 43.1 Mean Consec 1.3 5.0 3.0 1.0 2.0 2.1 1.3 2.0 2.6 2.2 2.4 1.0 Monthly Average: 2.2 Max Consec 3 5 3 1 2 5 2 2 4 7 4 1 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.