1996 Flagstaff Nighttime Cloudiness Summary Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Yr (nights) Photometric 3 2 3 2 10 8 0 4 6 12 7 4 61 Monthly Average: 5.1 Partial 9 3 10 9 6 7 0 5 5 7 9 8 78 Monthly Average: 6.5 Spectroscopic 7 7 6 12 10 6 6 6 4 3 3 4 74 Monthly Average: 6.2 Cloudy 12 17 12 7 5 9 25 16 15 9 11 15 152 Monthly Average: 12.7 -------------------------------------------------------------------------------- Clear Hours 97 36 72 64 102 86 0 54 85 160 128 100 984 Monthly Average: 82.0 Clear+Dark Hours 55 22 41 24 30 42 0 24 24 102 75 71 510 Monthly Average: 42.5 Mean Consec 1.5 1.0 1.0 1.0 1.4 1.6 0 2.0 2.0 3.0 1.4 1.3 Monthly Average: 1.4 Max Consec 2 1 1 1 3 3 0 3 3 7 2 2 Monthly Average: 2.3 -------------------------------------------------------------------------------- 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.