1994 Flagstaff Nighttime Cloudiness Summary Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Yr (nights) Photometric 7 5 3 4 8 12 11 1 7 9 6 10 83 Monthly Average: 6.9 Partial 4 6 5 4 6 1 2 8 3 8 8 3 58 Monthly Average: 4.8 Spectroscopic 5 1 4 6 7 6 1 5 8 8 5 2 58 Monthly Average: 4.8 Cloudy 15 16 19 16 10 11 17 17 12 6 11 16 166 Monthly Average: 13.8 -------------------------------------------------------------------------------- Clear Hours 83 90 62 34 91 89 84 42 67 143 115 130 1030 Monthly Average: 85.8 Clear+Dark Hours 57 47 21 28 51 56 75 16 35 84 59 45 574 Monthly Average: 47.8 Mean Consec 1.2 1.2 1.0 1.0 1.6 3.0 5.5 1.0 1.2 1.8 2.0 2.5 Monthly Average: 1.9 Max Consec 2 2 1 1 5 6 10 1 2 2 3 6 Monthly Average: 3.4 -------------------------------------------------------------------------------- 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.