2005 Flagstaff Nighttime Cloudiness Summary Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Yr (nights) Photometric 4 1 6 8 11 16 11 4 9 8 8 4 90 Monthly Average: 7.5 Partial 0 1 7 8 5 8 1 5 5 10 5 6 61 Monthly Average: 5.1 Spectroscopic 2 1 2 3 4 2 0 1 4 2 6 4 31 Monthly Average: 2.6 Cloudy 25 25 16 11 11 4 19 21 12 11 11 17 183 Monthly Average: 15.3 ------------------------------------------------------------------------------- Clear Hours 48 15 94 105 101 147 81 70 111 145 125 85 1127 Monthly Average: 93.9 Clear+Dark Hours 27 7 76 53 56 90 71 28 53 91 54 39 645 Monthly Average: 53.8 Mean Consec 1.0 1.0 2.0 2.0 3.7 2.7 11 1.3 1.5 1.6 1.3 1.0 Monthly Average: 2.5 Max Consec 1 1 4 5 5 4 11 2 2 2 2 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.