2006 Flagstaff Nighttime Cloudiness Summary Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Yr (nights) Photometric 9 8 0 12 16 9 1 5 6 9 8 7 90 Monthly Average: 7.5 Partial 7 2 2 3 2 5 2 1 1 7 6 5 43 Monthly Average: 3.6 Spectroscopic 6 7 4 2 5 6 0 4 10 5 5 5 59 Monthly Average: 4.9 Cloudy 9 11 25 13 8 10 28 21 13 10 11 14 173 Monthly Average: 14.4 ------------------------------------------------------------------------------- Clear Hours 161 108 10 124 131 85 15 46 67 149 133 115 1144 Monthly Average: 95.3 Clear+Dark Hours 80 37 0 63 64 34 2 29 62 93 77 21 562 Monthly Average: 46.8 Mean Consec 1.5 2.0 0 2.4 2.7 3.0 1.0 2.5 3.0 2.3 2.0 7.0 Monthly Average: 2.5 Max Consec 3 3 0 4 5 6 1 4 4 5 3 7 Monthly Average: 3.8 ------------------------------------------------------------------------------- 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.