High Level (Cirriform) Frequency of Occurrence (%) October (1954 - 1997) Night, Ship Observations Only Global Average: 27.9 Zonal Averages 16 zones Lat.N Average 85 53.2 75 29.9 65 23.4 55 24.6 45 26.1 35 25.7 25 24.2 15 32.4 5 36.8 -5 28.0 -15 20.6 -25 23.4 -35 25.6 -45 28.1 -55 24.0 -65 40.0 Grid Box Averages 307 filled boxes Box # Lat.N Lon.E Average 1 85 60 43.0 2 85 180 62.1 3 85 300 54.4 4 75 20 19.2 5 75 60 18.9 8 75 180 35.9 9 75 220 43.1 10 75 260 44.1 11 75 300 36.9 12 75 340 16.8 13 65 10 22.1 14 65 30 23.1 15 65 50 23.7 21 65 170 20.0 22 65 190 16.7 26 65 270 46.0 27 65 290 25.5 28 65 310 19.2 29 65 330 22.6 30 65 350 22.0 31 55 10 28.2 32 55 30 25.2 38 55 150 22.5 39 55 170 22.8 40 55 190 28.2 41 55 210 22.7 42 55 230 30.0 45 55 290 29.0 46 55 310 22.7 47 55 330 22.3 48 55 350 26.4 49 45 5 35.0 50 45 15 25.1 51 45 25 20.7 52 45 35 12.5 54 45 55 13.0 62 45 135 19.1 63 45 145 21.4 64 45 155 25.6 65 45 165 25.8 66 45 175 28.1 67 45 185 31.2 68 45 195 28.1 69 45 205 27.3 70 45 215 31.1 71 45 225 28.0 72 45 235 28.8 77 45 285 24.4 78 45 295 22.7 79 45 305 26.0 80 45 315 24.3 81 45 325 24.7 82 45 335 24.6 83 45 345 24.3 84 45 355 27.1 85 35 5 31.9 86 35 15 22.5 87 35 25 17.4 88 35 35 14.2 97 35 125 21.2 98 35 135 27.5 99 35 145 29.7 100 35 155 26.3 101 35 165 28.2 102 35 175 31.4 103 35 185 34.5 104 35 195 25.4 105 35 205 25.6 106 35 215 25.8 107 35 225 22.0 108 35 235 16.3 109 35 245 14.3 112 35 275 29.8 113 35 285 27.6 114 35 295 26.8 115 35 305 28.0 116 35 315 28.4 117 35 325 24.8 118 35 335 24.2 119 35 345 22.5 120 35 355 25.6 124 25 35 9.5 125 25 45 7.0 126 25 55 6.5 127 25 65 5.3 129 25 85 36.2 132 25 115 21.0 133 25 125 20.1 134 25 135 29.0 135 25 145 24.6 136 25 155 21.7 137 25 165 23.4 138 25 175 24.6 139 25 185 30.1 140 25 195 25.6 141 25 205 24.8 142 25 215 22.4 143 25 225 23.0 144 25 235 20.7 145 25 245 16.3 146 25 255 24.5 147 25 265 32.3 148 25 275 37.7 149 25 285 32.3 150 25 295 31.0 151 25 305 26.2 152 25 315 27.0 153 25 325 22.0 154 25 335 18.4 155 25 345 18.9 160 15 35 11.6 161 15 45 12.5 162 15 55 9.6 163 15 65 17.0 164 15 75 30.7 165 15 85 44.9 166 15 95 55.6 167 15 105 40.0 168 15 115 31.8 169 15 125 35.5 170 15 135 39.9 171 15 145 37.8 172 15 155 32.2 173 15 165 29.6 174 15 175 31.5 175 15 185 34.0 176 15 195 36.4 177 15 205 30.5 178 15 215 31.0 179 15 225 29.0 180 15 235 23.2 181 15 245 34.5 182 15 255 34.5 183 15 265 45.6 184 15 275 54.2 185 15 285 38.4 186 15 295 33.5 187 15 305 30.4 188 15 315 29.4 189 15 325 24.6 190 15 335 27.1 191 15 345 27.6 193 5 5 40.6 197 5 45 15.2 198 5 55 15.5 199 5 65 26.2 200 5 75 41.8 201 5 85 53.6 202 5 95 66.6 203 5 105 52.3 204 5 115 50.8 205 5 125 48.4 206 5 135 59.7 207 5 145 49.9 208 5 155 44.8 209 5 165 41.8 210 5 175 44.6 211 5 185 48.4 212 5 195 29.0 213 5 205 26.1 214 5 215 23.4 215 5 225 26.2 216 5 235 20.8 217 5 245 20.1 218 5 255 22.7 219 5 265 44.3 220 5 275 55.5 221 5 285 51.2 223 5 305 33.4 224 5 315 26.9 225 5 325 23.4 226 5 335 28.9 227 5 345 27.4 228 5 355 27.5 229 -5 5 24.5 230 -5 15 16.6 233 -5 45 12.8 234 -5 55 19.5 235 -5 65 41.3 236 -5 75 42.6 237 -5 85 58.3 238 -5 95 58.4 239 -5 105 50.5 240 -5 115 44.0 241 -5 125 31.0 242 -5 135 36.6 243 -5 145 45.4 244 -5 155 39.8 245 -5 165 51.4 246 -5 175 48.6 247 -5 185 42.0 248 -5 195 26.9 249 -5 205 18.3 250 -5 215 19.9 251 -5 225 4.9 252 -5 235 8.2 253 -5 245 8.1 254 -5 255 9.5 255 -5 265 16.4 256 -5 275 35.5 260 -5 315 21.6 261 -5 325 12.9 262 -5 335 9.8 263 -5 345 9.1 264 -5 355 12.1 265 -15 5 16.7 266 -15 15 18.0 268 -15 35 12.7 269 -15 45 12.6 270 -15 55 12.2 271 -15 65 15.1 272 -15 75 27.3 273 -15 85 38.3 274 -15 95 35.1 275 -15 105 16.6 276 -15 115 12.3 277 -15 125 17.0 278 -15 135 25.5 279 -15 145 22.6 280 -15 155 17.1 281 -15 165 28.5 282 -15 175 36.0 283 -15 185 35.2 284 -15 195 26.9 285 -15 205 23.7 286 -15 215 20.1 287 -15 225 13.2 288 -15 235 11.6 289 -15 245 8.2 290 -15 255 11.0 292 -15 275 17.5 293 -15 285 27.2 297 -15 325 22.1 298 -15 335 18.0 299 -15 345 16.5 300 -15 355 19.0 301 -25 5 23.9 302 -25 15 20.5 304 -25 35 18.6 305 -25 45 18.4 306 -25 55 20.5 307 -25 65 20.9 308 -25 75 16.4 309 -25 85 18.0 310 -25 95 22.4 311 -25 105 17.6 312 -25 115 14.1 316 -25 155 13.4 317 -25 165 19.7 318 -25 175 29.7 319 -25 185 31.8 320 -25 195 32.2 321 -25 205 19.4 322 -25 215 25.5 323 -25 225 33.5 324 -25 235 30.9 325 -25 245 16.4 328 -25 275 18.4 329 -25 285 16.9 332 -25 315 37.1 333 -25 325 26.3 334 -25 335 29.5 335 -25 345 28.1 336 -25 355 29.0 337 -35 5 38.6 338 -35 15 26.6 339 -35 25 21.5 340 -35 35 19.8 341 -35 45 26.6 342 -35 55 25.2 343 -35 65 22.9 344 -35 75 20.5 345 -35 85 27.6 346 -35 95 23.5 347 -35 105 25.4 348 -35 115 20.5 349 -35 125 21.4 350 -35 135 23.0 351 -35 145 24.9 352 -35 155 21.6 353 -35 165 23.2 354 -35 175 31.1 355 -35 185 30.1 356 -35 195 33.1 357 -35 205 19.7 358 -35 215 29.3 364 -35 275 21.1 365 -35 285 18.1 367 -35 305 24.4 368 -35 315 23.4 369 -35 325 25.4 370 -35 335 24.4 371 -35 345 32.6 372 -35 355 35.0 387 -45 145 26.7 388 -45 155 26.9 389 -45 165 18.7 390 -45 175 31.1 391 -45 185 31.2 401 -45 285 28.3 402 -45 295 29.4 403 -45 305 32.4 417 -55 170 13.8 423 -55 290 34.1 424 -55 310 33.1 425 -55 330 16.9 432 -65 110 40.0