High Level (Cirriform) Frequency of Occurrence (%) March, April, May (1954 - 1997) , Ship Observations Only Global Average: 34.1 Zonal Averages 17 zones Lat.N Average 85 59.3 75 44.4 65 35.2 55 35.2 45 34.8 35 35.0 25 29.9 15 30.9 5 42.9 -5 40.1 -15 32.6 -25 29.8 -35 30.5 -45 30.0 -55 30.2 -65 34.5 -75 40.0 Grid Box Averages 393 filled boxes Box # Lat.N Lon.E Average 1 85 60 58.6 2 85 180 60.2 3 85 300 58.9 4 75 20 31.0 5 75 60 27.7 6 75 100 28.6 7 75 140 49.1 8 75 180 54.9 9 75 220 73.7 10 75 260 46.1 11 75 300 44.3 12 75 340 25.4 13 65 10 34.8 14 65 30 34.2 15 65 50 38.6 16 65 70 34.9 21 65 170 28.9 22 65 190 31.3 23 65 210 40.2 27 65 290 34.1 29 65 330 41.9 30 65 350 33.7 31 55 10 38.6 32 55 30 38.3 37 55 130 39.2 38 55 150 29.9 39 55 170 30.0 40 55 190 34.2 41 55 210 35.9 42 55 230 36.3 45 55 290 36.6 46 55 310 37.0 47 55 330 35.4 48 55 350 42.0 49 45 5 43.7 50 45 15 39.0 51 45 25 29.0 52 45 35 23.8 53 45 45 28.8 54 45 55 22.6 61 45 125 27.9 62 45 135 25.7 63 45 145 28.7 64 45 155 31.1 65 45 165 33.2 66 45 175 34.2 67 45 185 36.6 68 45 195 38.7 69 45 205 38.2 70 45 215 37.7 71 45 225 33.7 72 45 235 35.4 77 45 285 36.3 78 45 295 38.9 79 45 305 37.3 80 45 315 36.5 81 45 325 33.9 82 45 335 34.4 83 45 345 33.8 84 45 355 36.4 85 35 5 37.5 86 35 15 33.7 87 35 25 27.4 88 35 35 24.6 89 35 45 31.2 90 35 55 25.1 96 35 115 24.6 97 35 125 30.9 98 35 135 37.5 99 35 145 35.2 100 35 155 35.2 101 35 165 37.9 102 35 175 38.7 103 35 185 41.5 104 35 195 41.2 105 35 205 39.8 106 35 215 35.3 107 35 225 31.6 108 35 235 28.1 109 35 245 28.1 112 35 275 41.8 113 35 285 38.7 114 35 295 34.5 115 35 305 33.9 116 35 315 36.8 117 35 325 35.2 118 35 335 31.9 119 35 345 28.3 120 35 355 34.8 124 25 35 21.5 125 25 45 24.8 126 25 55 24.2 127 25 65 18.9 128 25 75 18.9 129 25 85 30.5 130 25 95 52.3 131 25 105 36.5 132 25 115 34.1 133 25 125 32.1 134 25 135 32.3 135 25 145 31.0 136 25 155 27.5 137 25 165 27.9 138 25 175 28.2 139 25 185 29.8 140 25 195 29.8 141 25 205 28.6 142 25 215 30.4 143 25 225 33.3 144 25 235 31.1 145 25 245 32.7 146 25 255 37.0 147 25 265 41.3 148 25 275 37.5 149 25 285 34.8 150 25 295 29.1 151 25 305 28.6 152 25 315 28.3 153 25 325 26.1 154 25 335 22.6 155 25 345 23.3 156 25 355 32.6 160 15 35 18.4 161 15 45 22.4 162 15 55 17.6 163 15 65 16.8 164 15 75 24.6 165 15 85 33.6 166 15 95 38.1 167 15 105 43.9 168 15 115 31.0 169 15 125 32.2 170 15 135 31.7 171 15 145 33.1 172 15 155 28.1 173 15 165 31.4 174 15 175 28.1 175 15 185 32.5 176 15 195 32.8 177 15 205 32.5 178 15 215 35.9 179 15 225 38.6 180 15 235 35.7 181 15 245 32.4 182 15 255 35.2 183 15 265 38.9 184 15 275 41.0 185 15 285 34.2 186 15 295 28.5 187 15 305 26.7 188 15 315 26.8 189 15 325 26.9 190 15 335 24.2 191 15 345 26.1 193 5 5 49.3 197 5 45 29.1 198 5 55 27.0 199 5 65 27.7 200 5 75 38.7 201 5 85 52.7 202 5 95 63.2 203 5 105 50.9 204 5 115 49.5 205 5 125 49.6 206 5 135 53.8 207 5 145 53.1 208 5 155 53.1 209 5 165 49.7 210 5 175 51.4 211 5 185 49.8 212 5 195 40.4 213 5 205 42.2 214 5 215 36.3 215 5 225 37.6 216 5 235 36.6 217 5 245 35.3 218 5 255 32.4 219 5 265 40.6 220 5 275 50.1 221 5 285 48.7 222 5 295 33.4 223 5 305 36.1 224 5 315 40.2 225 5 325 37.2 226 5 335 31.5 227 5 345 37.6 228 5 355 45.8 229 -5 5 38.3 230 -5 15 36.4 232 -5 35 37.6 233 -5 45 33.8 234 -5 55 34.1 235 -5 65 40.4 236 -5 75 46.3 237 -5 85 54.5 238 -5 95 57.9 239 -5 105 59.6 240 -5 115 55.7 241 -5 125 51.4 242 -5 135 52.2 243 -5 145 61.0 244 -5 155 56.4 245 -5 165 53.6 246 -5 175 51.0 247 -5 185 52.3 248 -5 195 41.0 249 -5 205 35.8 250 -5 215 32.9 251 -5 225 26.2 252 -5 235 22.7 253 -5 245 22.1 254 -5 255 21.2 255 -5 265 24.9 256 -5 275 38.0 257 -5 285 40.7 260 -5 315 55.9 261 -5 325 41.5 262 -5 335 30.4 263 -5 345 26.8 264 -5 355 31.2 265 -15 5 18.7 266 -15 15 25.3 268 -15 35 23.2 269 -15 45 32.6 270 -15 55 33.2 271 -15 65 32.5 272 -15 75 35.0 273 -15 85 37.9 274 -15 95 42.5 275 -15 105 35.7 276 -15 115 30.2 277 -15 125 33.7 278 -15 135 47.7 279 -15 145 41.2 280 -15 155 39.9 281 -15 165 42.6 282 -15 175 44.6 283 -15 185 51.1 284 -15 195 47.3 285 -15 205 42.0 286 -15 215 35.0 287 -15 225 27.6 288 -15 235 24.8 289 -15 245 20.6 290 -15 255 20.3 291 -15 265 20.6 292 -15 275 26.5 293 -15 285 36.3 297 -15 325 36.7 298 -15 335 23.4 299 -15 345 18.3 300 -15 355 20.5 301 -25 5 16.3 302 -25 15 16.3 304 -25 35 22.5 305 -25 45 25.9 306 -25 55 32.5 307 -25 65 26.1 308 -25 75 24.1 309 -25 85 24.4 310 -25 95 27.2 311 -25 105 26.0 312 -25 115 25.9 315 -25 145 27.4 316 -25 155 27.5 317 -25 165 30.9 318 -25 175 37.0 319 -25 185 39.1 320 -25 195 40.2 321 -25 205 43.5 322 -25 215 43.0 323 -25 225 40.4 324 -25 235 33.1 325 -25 245 31.4 326 -25 255 30.6 327 -25 265 27.2 328 -25 275 18.2 329 -25 285 22.6 332 -25 315 38.4 333 -25 325 35.4 334 -25 335 31.5 335 -25 345 26.1 336 -25 355 21.3 337 -35 5 31.3 338 -35 15 24.6 339 -35 25 29.1 340 -35 35 26.3 341 -35 45 26.8 342 -35 55 28.0 343 -35 65 30.7 344 -35 75 30.0 345 -35 85 27.7 346 -35 95 29.2 347 -35 105 26.8 348 -35 115 28.6 349 -35 125 32.0 350 -35 135 31.4 351 -35 145 32.9 352 -35 155 29.9 353 -35 165 28.4 354 -35 175 29.8 355 -35 185 32.5 356 -35 195 32.6 357 -35 205 31.1 358 -35 215 34.8 359 -35 225 39.2 360 -35 235 39.0 361 -35 245 36.6 362 -35 255 30.0 363 -35 265 23.8 364 -35 275 23.6 365 -35 285 25.0 366 -35 295 38.2 367 -35 305 30.6 368 -35 315 31.3 369 -35 325 32.2 370 -35 335 32.2 371 -35 345 34.8 372 -35 355 34.4 373 -45 5 30.4 374 -45 15 33.0 375 -45 25 29.3 376 -45 35 35.0 377 -45 45 30.6 378 -45 55 30.1 379 -45 65 26.4 380 -45 75 26.1 381 -45 85 24.6 382 -45 95 35.5 383 -45 105 34.6 384 -45 115 31.6 385 -45 125 37.8 386 -45 135 33.6 387 -45 145 34.6 388 -45 155 31.5 389 -45 165 26.4 390 -45 175 33.6 391 -45 185 31.0 392 -45 195 34.7 393 -45 205 24.7 394 -45 215 27.4 395 -45 225 31.2 396 -45 235 34.8 397 -45 245 32.9 398 -45 255 22.7 399 -45 265 16.6 400 -45 275 18.1 401 -45 285 22.0 402 -45 295 38.0 403 -45 305 31.0 404 -45 315 31.0 405 -45 325 30.6 406 -45 335 33.5 407 -45 345 28.9 408 -45 355 27.5 409 -55 10 32.0 410 -55 30 29.9 411 -55 50 19.1 412 -55 70 24.6 413 -55 90 30.5 414 -55 110 33.4 415 -55 130 38.4 416 -55 150 24.9 417 -55 170 20.9 418 -55 190 36.6 419 -55 210 22.8 420 -55 230 33.3 421 -55 250 37.4 422 -55 270 33.5 423 -55 290 39.5 424 -55 310 39.6 425 -55 330 22.5 426 -55 350 26.2 427 -65 10 37.4 428 -65 30 39.4 429 -65 50 28.4 430 -65 70 25.6 431 -65 90 33.0 432 -65 110 41.0 433 -65 130 37.7 434 -65 150 28.5 435 -65 170 32.3 436 -65 190 39.9 437 -65 210 28.2 438 -65 230 38.4 440 -65 270 33.6 441 -65 290 53.4 442 -65 310 24.8 443 -65 330 30.8 444 -65 350 35.2 449 -75 180 29.6 450 -75 220 48.5 453 -75 340 45.6