High Level (Cirriform) Frequency of Occurrence (%) February (1954 - 1997) Night, Ship Observations Only Global Average: 28.5 Zonal Averages 17 zones Lat.N Average 85 49.9 75 36.8 65 20.1 55 21.3 45 22.2 35 23.7 25 18.7 15 18.1 5 32.0 -5 35.4 -15 33.3 -25 26.5 -35 25.4 -45 31.3 -55 32.3 -65 38.0 -75 42.5 Grid Box Averages 322 filled boxes Box # Lat.N Lon.E Average 2 85 180 49.9 4 75 20 16.6 8 75 180 55.0 13 65 10 17.1 21 65 170 10.4 22 65 190 8.6 29 65 330 31.8 30 65 350 21.6 31 55 10 19.4 32 55 30 22.2 38 55 150 18.4 39 55 170 21.3 40 55 190 18.6 41 55 210 22.7 42 55 230 28.7 46 55 310 15.9 47 55 330 24.1 48 55 350 25.7 49 45 5 28.3 50 45 15 24.6 51 45 25 24.7 52 45 35 18.1 62 45 135 15.6 63 45 145 17.5 64 45 155 18.7 65 45 165 18.9 66 45 175 19.8 67 45 185 23.0 68 45 195 25.2 69 45 205 27.8 70 45 215 23.8 71 45 225 21.9 72 45 235 26.3 77 45 285 22.9 78 45 295 21.3 79 45 305 21.9 80 45 315 21.4 81 45 325 22.5 82 45 335 24.1 83 45 345 23.1 84 45 355 24.2 85 35 5 25.9 86 35 15 22.8 87 35 25 18.4 88 35 35 17.1 97 35 125 20.3 98 35 135 19.4 99 35 145 16.6 100 35 155 17.2 101 35 165 18.2 102 35 175 20.1 103 35 185 25.4 104 35 195 25.4 105 35 205 28.3 106 35 215 25.5 107 35 225 26.2 108 35 235 25.6 109 35 245 30.6 112 35 275 33.1 113 35 285 27.2 114 35 295 25.7 115 35 305 25.4 116 35 315 28.0 117 35 325 27.7 118 35 335 26.8 119 35 345 22.5 120 35 355 24.0 124 25 35 13.3 125 25 45 18.2 126 25 55 13.4 127 25 65 11.1 132 25 115 16.2 133 25 125 15.2 134 25 135 13.1 135 25 145 15.8 136 25 155 14.7 137 25 165 14.7 138 25 175 13.0 139 25 185 17.7 140 25 195 14.8 141 25 205 16.4 142 25 215 21.7 143 25 225 27.6 144 25 235 27.8 145 25 245 26.6 146 25 255 28.3 147 25 265 26.7 148 25 275 27.0 149 25 285 20.6 150 25 295 16.4 151 25 305 15.2 152 25 315 19.1 153 25 325 19.6 154 25 335 18.0 155 25 345 19.7 160 15 35 8.8 161 15 45 10.6 162 15 55 9.6 163 15 65 9.9 164 15 75 16.0 165 15 85 17.0 166 15 95 25.4 167 15 105 27.8 168 15 115 17.9 169 15 125 19.2 170 15 135 23.9 171 15 145 24.2 172 15 155 20.1 173 15 165 14.0 174 15 175 15.6 175 15 185 15.7 176 15 195 15.1 177 15 205 11.6 178 15 215 19.2 179 15 225 18.3 180 15 235 26.6 181 15 245 26.3 182 15 255 22.1 183 15 265 17.4 184 15 275 24.2 185 15 285 16.1 186 15 295 13.2 187 15 305 13.8 188 15 315 13.8 189 15 325 21.6 190 15 335 18.7 191 15 345 20.8 193 5 5 34.5 197 5 45 20.1 198 5 55 16.4 199 5 65 19.5 200 5 75 25.0 201 5 85 35.8 202 5 95 49.6 203 5 105 40.6 204 5 115 37.6 205 5 125 43.6 206 5 135 54.6 207 5 145 47.6 208 5 155 54.6 209 5 165 50.9 210 5 175 38.4 211 5 185 45.0 212 5 195 32.8 213 5 205 25.2 214 5 215 21.4 215 5 225 23.9 217 5 245 16.5 218 5 255 17.4 219 5 265 24.1 220 5 275 32.5 221 5 285 33.2 223 5 305 23.1 224 5 315 27.9 225 5 325 24.6 226 5 335 22.1 227 5 345 21.4 228 5 355 26.1 229 -5 5 36.3 230 -5 15 45.4 233 -5 45 29.6 234 -5 55 29.6 235 -5 65 41.1 236 -5 75 43.4 237 -5 85 46.2 238 -5 95 56.3 239 -5 105 60.9 240 -5 115 59.5 241 -5 125 54.8 242 -5 135 54.4 243 -5 145 65.2 244 -5 155 53.4 245 -5 165 56.0 246 -5 175 53.2 247 -5 185 53.4 248 -5 195 46.4 249 -5 205 25.0 250 -5 215 16.7 251 -5 225 15.8 252 -5 235 12.4 253 -5 245 13.1 254 -5 255 12.7 255 -5 265 15.0 256 -5 275 38.0 257 -5 285 45.6 260 -5 315 44.4 261 -5 325 31.1 262 -5 335 17.3 263 -5 345 12.8 264 -5 355 17.6 265 -15 5 21.1 266 -15 15 39.9 268 -15 35 35.0 269 -15 45 43.9 270 -15 55 43.9 271 -15 65 36.4 272 -15 75 35.2 273 -15 85 30.4 274 -15 95 41.6 275 -15 105 36.3 276 -15 115 43.5 277 -15 125 40.0 278 -15 135 50.5 279 -15 145 42.5 280 -15 155 37.0 281 -15 165 37.3 282 -15 175 50.7 283 -15 185 57.2 284 -15 195 60.2 285 -15 205 45.3 286 -15 215 34.9 287 -15 225 27.0 288 -15 235 22.1 289 -15 245 12.2 290 -15 255 9.8 291 -15 265 12.3 292 -15 275 28.8 293 -15 285 47.6 297 -15 325 30.4 298 -15 335 17.6 299 -15 345 12.1 300 -15 355 17.5 301 -25 5 12.2 302 -25 15 14.2 304 -25 35 19.3 305 -25 45 28.0 306 -25 55 32.9 307 -25 65 29.7 308 -25 75 23.3 309 -25 85 24.9 310 -25 95 24.7 311 -25 105 27.8 312 -25 115 22.7 316 -25 155 25.6 317 -25 165 25.8 318 -25 175 38.7 319 -25 185 44.9 320 -25 195 44.4 321 -25 205 40.3 322 -25 215 38.7 323 -25 225 30.6 324 -25 235 32.1 325 -25 245 18.2 326 -25 255 8.4 327 -25 265 18.8 328 -25 275 17.4 329 -25 285 21.9 332 -25 315 36.9 333 -25 325 30.1 334 -25 335 21.0 335 -25 345 21.2 336 -25 355 12.4 337 -35 5 19.8 338 -35 15 16.8 339 -35 25 21.7 340 -35 35 23.0 341 -35 45 19.1 342 -35 55 23.5 343 -35 65 19.1 344 -35 75 29.4 345 -35 85 29.8 346 -35 95 28.5 347 -35 105 27.2 348 -35 115 20.6 349 -35 125 20.8 350 -35 135 20.4 351 -35 145 22.8 352 -35 155 25.3 353 -35 165 20.9 354 -35 175 28.3 355 -35 185 36.5 356 -35 195 38.0 357 -35 205 35.4 358 -35 215 35.5 363 -35 265 20.4 364 -35 275 16.1 365 -35 285 18.8 367 -35 305 25.2 368 -35 315 27.9 369 -35 325 32.4 370 -35 335 21.6 371 -35 345 26.8 372 -35 355 25.3 379 -45 65 24.8 380 -45 75 37.7 387 -45 145 31.1 388 -45 155 23.6 389 -45 165 20.0 390 -45 175 32.7 391 -45 185 36.4 392 -45 195 42.4 393 -45 205 36.4 400 -45 275 20.5 401 -45 285 26.8 402 -45 295 39.9 403 -45 305 35.0 409 -55 10 34.1 412 -55 70 26.3 413 -55 90 40.0 416 -55 150 35.0 417 -55 170 25.2 423 -55 290 41.7 424 -55 310 41.7 425 -55 330 22.8 426 -55 350 25.6 427 -65 10 42.7 428 -65 30 43.5 429 -65 50 34.3 430 -65 70 33.3 431 -65 90 32.4 432 -65 110 32.8 433 -65 130 42.1 434 -65 150 31.0 435 -65 170 28.8 437 -65 210 40.4 441 -65 290 52.5 442 -65 310 42.4 444 -65 350 34.1 449 -75 180 43.3 450 -75 220 40.7 452 -75 300 47.0 453 -75 340 39.4