1985 Flagstaff Nighttime Cloudiness Summary Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Yr (nights) Photometric 9 6 4 5 9 14 1 9 6 4 5 4 83 Monthly Average: 6.9 Partial 0 2 4 7 1 4 6 6 1 6 4 5 46 Monthly Average: 3.8 Spectroscopic 4 3 5 7 5 5 2 5 8 3 7 11 55 Monthly Average: 4.6 Cloudy 18 17 18 11 16 7 22 11 15 18 14 11 178 Monthly Average: 14.8 -------------------------------------------------------------------------------- Clear Hours 108 80 53 85 74 113 34 104 64 78 81 79 953 Monthly Average: 79.4 Clear+Dark Hours 51 37 41 49 34 65 8 67 38 46 50 33 519 Monthly Average: 43.3 Mean Consec 2.3 2.0 1.0 1.7 1.1 2.3 1.0 1.8 1.5 1.0 1.3 1.3 Monthly Average: 1.5 Max Consec 4 4 1 3 2 5 1 4 3 1 2 2 Monthly Average: 2.7 -------------------------------------------------------------------------------- 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.