AVAILABLE ALL-SKY DATA IN 1975 observation hours per month STATION JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC films (*) OULU 188 157 186 125 0 0 0 0 82 70 172 211 26 SODANKYLA 164 159 157 100 0 0 0 0 148 154 245 283 40 MUONIO 123 138 72 52 0 0 0 5 69 92 135 183 22 IVALO 78 104 68 41 0 0 0 0 87 36 95 197 21 KEVO 90 138 46 62 0 0 0 4 98 69 179 133 26 HANKASALMI 0 0 0 0 0 0 0 0 0 0 0 0 0 KILPISJARVI 0 0 0 0 0 0 0 0 0 0 0 0 0 KIRUNA 0 0 0 0 0 0 0 0 0 0 0 0 0 TROMSO 0 0 0 0 0 0 0 0 0 0 0 0 0 HORNSUND 0 0 0 0 0 0 0 0 0 0 0 0 0 ANDOYA 0 0 0 0 0 0 0 0 0 0 0 0 0 GEORG FORSTER 0 0 0 0 0 0 0 0 0 0 0 0 0 (*) analyzed films per year