High Level (Cirriform) Frequency of Occurrence (%) December, January, February (1954 - 1997) Night, Ship Observations Only Global Average: 29.1 Zonal Averages 17 zones Lat.N Average 85 53.3 75 38.1 65 19.1 55 21.2 45 22.3 35 23.5 25 19.5 15 20.3 5 32.4 -5 34.3 -15 32.2 -25 27.6 -35 27.6 -45 31.0 -55 34.6 -65 39.4 -75 46.2 Grid Box Averages 376 filled boxes Box # Lat.N Lon.E Average 1 85 60 66.5 2 85 180 48.5 3 85 300 42.0 4 75 20 15.7 5 75 60 12.4 7 75 140 47.5 8 75 180 48.7 9 75 220 78.1 12 75 340 12.9 13 65 10 16.7 14 65 30 21.5 15 65 50 22.4 21 65 170 12.2 22 65 190 11.3 23 65 210 17.8 29 65 330 27.7 30 65 350 18.8 31 55 10 18.0 32 55 30 21.6 38 55 150 19.3 39 55 170 20.4 40 55 190 19.1 41 55 210 21.4 42 55 230 24.3 46 55 310 19.7 47 55 330 22.9 48 55 350 25.9 49 45 5 27.4 50 45 15 24.3 51 45 25 22.4 52 45 35 17.9 53 45 45 15.6 54 45 55 17.3 62 45 135 14.4 63 45 145 17.1 64 45 155 18.7 65 45 165 18.0 66 45 175 21.1 67 45 185 22.2 68 45 195 24.8 69 45 205 26.6 70 45 215 26.7 71 45 225 24.9 72 45 235 26.4 77 45 285 24.5 78 45 295 21.1 79 45 305 21.7 80 45 315 21.9 81 45 325 22.4 82 45 335 23.4 83 45 345 22.6 84 45 355 23.5 85 35 5 25.1 86 35 15 22.5 87 35 25 19.5 88 35 35 19.6 96 35 115 16.1 97 35 125 16.8 98 35 135 16.4 99 35 145 15.8 100 35 155 17.0 101 35 165 18.0 102 35 175 19.4 103 35 185 24.6 104 35 195 25.4 105 35 205 28.8 106 35 215 28.7 107 35 225 26.2 108 35 235 24.9 109 35 245 27.0 112 35 275 34.6 113 35 285 27.1 114 35 295 25.4 115 35 305 26.4 116 35 315 27.6 117 35 325 27.9 118 35 335 26.5 119 35 345 23.0 120 35 355 23.4 124 25 35 15.9 125 25 45 18.2 126 25 55 16.0 127 25 65 14.6 128 25 75 11.0 129 25 85 20.9 130 25 95 16.4 132 25 115 14.7 133 25 125 15.1 134 25 135 13.2 135 25 145 15.8 136 25 155 15.3 137 25 165 14.3 138 25 175 13.7 139 25 185 18.2 140 25 195 17.4 141 25 205 18.8 142 25 215 23.7 143 25 225 27.7 144 25 235 26.1 145 25 245 28.3 146 25 255 30.5 147 25 265 30.6 148 25 275 29.1 149 25 285 22.4 150 25 295 18.3 151 25 305 16.7 152 25 315 19.3 153 25 325 18.7 154 25 335 17.7 155 25 345 20.1 160 15 35 11.7 161 15 45 10.6 162 15 55 10.3 163 15 65 12.8 164 15 75 17.5 165 15 85 22.0 166 15 95 30.9 167 15 105 26.5 168 15 115 20.4 169 15 125 21.8 170 15 135 25.9 171 15 145 24.5 172 15 155 19.1 173 15 165 13.5 174 15 175 14.4 175 15 185 17.3 176 15 195 17.5 177 15 205 14.7 178 15 215 22.8 179 15 225 23.3 180 15 235 28.1 181 15 245 28.4 182 15 255 26.1 183 15 265 20.9 184 15 275 28.6 185 15 285 19.5 186 15 295 15.0 187 15 305 14.3 188 15 315 17.3 189 15 325 21.0 190 15 335 23.2 191 15 345 27.3 193 5 5 33.3 197 5 45 17.9 198 5 55 16.5 199 5 65 20.9 200 5 75 27.5 201 5 85 39.1 202 5 95 51.7 203 5 105 42.9 204 5 115 41.5 205 5 125 43.6 206 5 135 56.7 207 5 145 43.6 208 5 155 45.1 209 5 165 45.2 210 5 175 41.3 211 5 185 45.8 212 5 195 32.1 213 5 205 25.9 214 5 215 23.0 215 5 225 24.7 216 5 235 19.7 217 5 245 25.0 218 5 255 20.3 219 5 265 23.1 220 5 275 33.0 221 5 285 32.5 223 5 305 24.6 224 5 315 29.4 225 5 325 28.0 226 5 335 26.4 227 5 345 23.6 228 5 355 25.1 229 -5 5 33.8 230 -5 15 44.0 232 -5 35 41.7 233 -5 45 26.4 234 -5 55 31.6 235 -5 65 38.1 236 -5 75 43.4 237 -5 85 48.8 238 -5 95 56.3 239 -5 105 61.9 240 -5 115 58.5 241 -5 125 54.3 242 -5 135 52.7 243 -5 145 57.0 244 -5 155 51.0 245 -5 165 56.4 246 -5 175 55.8 247 -5 185 55.1 248 -5 195 42.1 249 -5 205 23.8 250 -5 215 17.4 251 -5 225 16.0 252 -5 235 11.9 253 -5 245 9.6 254 -5 255 10.5 255 -5 265 13.8 256 -5 275 34.8 257 -5 285 40.6 260 -5 315 36.1 261 -5 325 27.4 262 -5 335 15.7 263 -5 345 12.0 264 -5 355 18.1 265 -15 5 20.4 266 -15 15 33.8 268 -15 35 36.5 269 -15 45 41.9 270 -15 55 39.0 271 -15 65 33.3 272 -15 75 35.6 273 -15 85 36.0 274 -15 95 39.9 275 -15 105 37.2 276 -15 115 35.0 277 -15 125 40.6 278 -15 135 47.5 279 -15 145 41.6 280 -15 155 33.5 281 -15 165 40.1 282 -15 175 48.9 283 -15 185 55.0 284 -15 195 54.8 285 -15 205 42.1 286 -15 215 33.5 287 -15 225 25.3 288 -15 235 20.2 289 -15 245 17.1 290 -15 255 11.8 291 -15 265 15.0 292 -15 275 23.2 293 -15 285 44.4 297 -15 325 31.3 298 -15 335 16.5 299 -15 345 14.7 300 -15 355 18.4 301 -25 5 13.5 302 -25 15 15.0 304 -25 35 24.9 305 -25 45 27.0 306 -25 55 32.4 307 -25 65 25.9 308 -25 75 25.3 309 -25 85 23.9 310 -25 95 23.3 311 -25 105 25.0 312 -25 115 22.3 315 -25 145 24.1 316 -25 155 24.5 317 -25 165 28.3 318 -25 175 36.4 319 -25 185 40.0 320 -25 195 42.5 321 -25 205 41.5 322 -25 215 42.0 323 -25 225 32.9 324 -25 235 28.1 325 -25 245 20.8 326 -25 255 21.2 327 -25 265 26.2 328 -25 275 19.9 329 -25 285 20.6 332 -25 315 38.3 333 -25 325 33.8 334 -25 335 26.8 335 -25 345 23.8 336 -25 355 15.9 337 -35 5 23.5 338 -35 15 21.1 339 -35 25 27.3 340 -35 35 25.1 341 -35 45 20.0 342 -35 55 23.2 343 -35 65 22.8 344 -35 75 29.9 345 -35 85 29.9 346 -35 95 28.9 347 -35 105 28.3 348 -35 115 24.0 349 -35 125 23.9 350 -35 135 22.5 351 -35 145 23.4 352 -35 155 24.8 353 -35 165 27.5 354 -35 175 32.5 355 -35 185 34.3 356 -35 195 38.4 357 -35 205 38.9 358 -35 215 30.4 359 -35 225 36.7 360 -35 235 28.5 361 -35 245 25.4 362 -35 255 27.0 363 -35 265 23.4 364 -35 275 19.2 365 -35 285 19.2 367 -35 305 29.1 368 -35 315 28.8 369 -35 325 28.3 370 -35 335 31.7 371 -35 345 32.2 372 -35 355 28.3 373 -45 5 23.2 374 -45 15 35.4 375 -45 25 35.0 376 -45 35 32.5 377 -45 45 21.7 378 -45 55 18.1 379 -45 65 25.6 380 -45 75 36.4 381 -45 85 28.7 382 -45 95 30.2 383 -45 105 32.1 384 -45 115 30.5 385 -45 125 31.4 386 -45 135 31.9 387 -45 145 29.6 388 -45 155 31.1 389 -45 165 30.5 390 -45 175 36.7 391 -45 185 36.6 392 -45 195 42.0 393 -45 205 36.4 394 -45 215 40.8 399 -45 265 24.9 400 -45 275 21.9 401 -45 285 28.5 402 -45 295 41.6 403 -45 305 37.8 404 -45 315 36.1 405 -45 325 21.8 406 -45 335 29.0 407 -45 345 27.0 408 -45 355 30.1 409 -55 10 34.3 410 -55 30 32.3 411 -55 50 39.5 412 -55 70 32.1 413 -55 90 41.9 414 -55 110 31.2 415 -55 130 37.6 416 -55 150 30.9 417 -55 170 26.1 418 -55 190 41.8 419 -55 210 35.0 421 -55 250 27.7 422 -55 270 34.9 423 -55 290 48.6 424 -55 310 39.3 425 -55 330 26.8 426 -55 350 31.2 427 -65 10 41.0 428 -65 30 43.5 429 -65 50 39.3 430 -65 70 33.1 431 -65 90 32.6 432 -65 110 36.7 433 -65 130 44.8 434 -65 150 38.0 435 -65 170 29.4 436 -65 190 43.8 437 -65 210 45.9 438 -65 230 34.6 439 -65 250 37.4 440 -65 270 30.6 441 -65 290 52.1 442 -65 310 42.8 443 -65 330 42.3 444 -65 350 39.8 449 -75 180 43.3 450 -75 220 41.3 452 -75 300 54.8 453 -75 340 49.2