AVAILABLE ALL-SKY DATA IN 1981 observation hours per month STATION JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC films (*) OULU 0 0 0 0 0 0 0 0 0 0 0 0 0 SODANKYLA 190 0 236 95 0 0 0 0 228 12 188 291 21 MUONIO 25 114 98 25 0 0 0 0 41 24 104 200 15 IVALO 0 0 0 0 0 0 0 0 0 0 0 0 0 KEVO 124 115 87 0 0 0 0 0 35 73 91 145 15 HANKASALMI 31 150 179 60 0 0 0 0 118 63 12 10 12 KILPISJARVI 171 257 170 22 0 0 0 0 88 145 216 331 32 KIRUNA 327 252 211 65 0 0 0 0 87 180 194 198 27 TROMSO 0 0 0 0 0 0 0 0 0 0 0 0 0 HORNSUND 98 13 23 0 0 0 0 0 2 41 92 100 19 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