1982 Flagstaff Nighttime Cloudiness Summary Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Yr (nights) Photometric 10 3 7 7 18 17 12 2 7 13 5 7 108 Monthly Average: 9.0 Partial 3 0 2 2 2 1 5 1 3 2 1 7 29 Monthly Average: 2.4 Spectroscopic 4 5 2 2 3 4 1 3 2 3 3 3 35 Monthly Average: 2.9 Cloudy 14 20 20 19 8 8 13 25 18 13 21 14 193 Monthly Average: 16.1 -------------------------------------------------------------------------------- Clear Hours 143 33 78 72 131 105 94 19 70 126 59 146 1076 Monthly Average: 89.7 Clear+Dark Hours 81 20 34 48 82 54 32 5 36 58 16 88 554 Monthly Average: 46.2 Mean Consec 2.5 1.7 1.4 1.4 3.0 2.1 4.0 1.0 1.1 3.3 1.7 1.2 Monthly Average: 2.0 Max Consec 4 2 3 3 5 5 8 1 2 10 3 2 Monthly Average: 4.2 -------------------------------------------------------------------------------- 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.