High Level (Cirriform) Frequency of Occurrence (%) March, April, May (1954 - 1997) Day, Ship Observations Only Global Average: 39.8 Zonal Averages 17 zones Lat.N Average 85 60.3 75 45.3 65 38.4 55 39.5 45 40.1 35 40.3 25 35.0 15 36.2 5 49.5 -5 46.9 -15 39.1 -25 36.1 -35 37.2 -45 35.8 -55 36.1 -65 38.2 -75 44.8 Grid Box Averages 389 filled boxes Box # Lat.N Lon.E Average 1 85 60 60.3 2 85 180 60.4 3 85 300 60.1 4 75 20 32.0 5 75 60 26.9 6 75 100 28.9 7 75 140 49.9 8 75 180 56.8 9 75 220 73.9 11 75 300 49.9 12 75 340 26.4 13 65 10 37.9 14 65 30 36.6 15 65 50 38.6 21 65 170 31.2 22 65 190 33.3 23 65 210 42.5 27 65 290 39.1 29 65 330 45.7 30 65 350 37.1 31 55 10 42.7 32 55 30 37.7 37 55 130 40.4 38 55 150 34.2 39 55 170 34.1 40 55 190 37.0 41 55 210 41.5 42 55 230 43.7 45 55 290 39.3 46 55 310 41.0 47 55 330 39.0 48 55 350 47.6 49 45 5 49.6 50 45 15 40.2 51 45 25 30.6 52 45 35 27.2 53 45 45 35.0 54 45 55 28.5 61 45 125 29.0 62 45 135 31.4 63 45 145 34.2 64 45 155 35.6 65 45 165 37.9 66 45 175 38.4 67 45 185 40.6 68 45 195 40.9 69 45 205 43.2 70 45 215 44.1 71 45 225 42.4 72 45 235 43.2 77 45 285 37.3 78 45 295 41.2 79 45 305 42.7 80 45 315 43.1 81 45 325 41.6 82 45 335 41.0 83 45 345 39.3 84 45 355 41.8 85 35 5 42.3 86 35 15 35.0 87 35 25 30.6 88 35 35 29.1 89 35 45 24.7 90 35 55 31.6 96 35 115 27.1 97 35 125 34.1 98 35 135 42.5 99 35 145 40.7 100 35 155 41.4 101 35 165 43.6 102 35 175 43.4 103 35 185 45.0 104 35 195 43.0 105 35 205 44.6 106 35 215 43.3 107 35 225 39.3 108 35 235 35.0 109 35 245 31.7 112 35 275 46.9 113 35 285 39.6 114 35 295 38.8 115 35 305 40.7 116 35 315 44.3 117 35 325 42.9 118 35 335 39.5 119 35 345 33.9 120 35 355 40.9 124 25 35 24.5 125 25 45 29.7 126 25 55 27.8 127 25 65 22.0 128 25 75 21.3 129 25 85 31.1 130 25 95 47.1 131 25 105 38.6 132 25 115 40.4 133 25 125 38.8 134 25 135 38.9 135 25 145 36.5 136 25 155 33.5 137 25 165 32.8 138 25 175 32.4 139 25 185 32.9 140 25 195 32.1 141 25 205 33.8 142 25 215 36.7 143 25 225 40.0 144 25 235 38.2 145 25 245 39.5 146 25 255 44.4 147 25 265 43.9 148 25 275 40.5 149 25 285 35.8 150 25 295 34.3 151 25 305 35.1 152 25 315 35.1 153 25 325 31.8 154 25 335 28.2 155 25 345 27.9 156 25 355 34.4 160 15 35 21.6 161 15 45 25.8 162 15 55 21.6 163 15 65 21.5 164 15 75 29.5 165 15 85 35.1 166 15 95 39.5 167 15 105 49.2 168 15 115 39.2 169 15 125 40.0 170 15 135 39.2 171 15 145 40.3 172 15 155 35.1 173 15 165 37.7 174 15 175 31.6 175 15 185 34.3 176 15 195 35.3 177 15 205 37.2 178 15 215 42.9 179 15 225 44.8 180 15 235 42.8 181 15 245 39.8 182 15 255 39.7 183 15 265 40.8 184 15 275 43.6 185 15 285 37.6 186 15 295 35.5 187 15 305 34.7 188 15 315 33.5 189 15 325 32.1 190 15 335 28.9 191 15 345 30.8 193 5 5 52.0 197 5 45 35.4 198 5 55 33.6 199 5 65 34.9 200 5 75 46.4 201 5 85 59.1 202 5 95 66.9 203 5 105 57.9 204 5 115 58.1 205 5 125 59.4 206 5 135 61.1 207 5 145 61.8 208 5 155 62.9 209 5 165 58.6 210 5 175 59.4 211 5 185 51.8 212 5 195 45.8 213 5 205 49.0 214 5 215 45.3 215 5 225 42.9 216 5 235 41.6 217 5 245 43.0 218 5 255 38.3 219 5 265 44.1 220 5 275 53.3 221 5 285 53.2 222 5 295 37.8 223 5 305 43.9 224 5 315 47.1 225 5 325 45.2 226 5 335 38.6 227 5 345 44.3 228 5 355 52.5 229 -5 5 40.4 230 -5 15 39.4 232 -5 35 52.9 233 -5 45 41.8 234 -5 55 43.7 235 -5 65 49.6 236 -5 75 54.9 237 -5 85 63.9 238 -5 95 63.0 239 -5 105 67.4 240 -5 115 65.6 241 -5 125 60.5 242 -5 135 61.0 243 -5 145 68.9 244 -5 155 67.3 245 -5 165 62.5 246 -5 175 60.1 247 -5 185 53.4 248 -5 195 47.4 249 -5 205 41.8 250 -5 215 40.2 251 -5 225 31.8 252 -5 235 27.9 253 -5 245 27.2 254 -5 255 27.0 255 -5 265 28.6 256 -5 275 41.0 257 -5 285 43.5 260 -5 315 59.7 261 -5 325 49.2 262 -5 335 38.8 263 -5 345 33.1 264 -5 355 36.9 265 -15 5 20.3 266 -15 15 26.7 268 -15 35 28.8 269 -15 45 40.1 270 -15 55 41.2 271 -15 65 41.4 272 -15 75 44.8 273 -15 85 45.7 274 -15 95 45.7 275 -15 105 42.3 276 -15 115 37.2 277 -15 125 41.8 278 -15 135 56.6 279 -15 145 50.6 280 -15 155 49.5 281 -15 165 52.8 282 -15 175 52.5 283 -15 185 54.3 284 -15 195 54.7 285 -15 205 51.4 286 -15 215 43.8 287 -15 225 34.3 288 -15 235 30.5 289 -15 245 26.1 290 -15 255 25.8 291 -15 265 24.0 292 -15 275 27.6 293 -15 285 39.9 297 -15 325 43.9 298 -15 335 30.3 299 -15 345 23.6 300 -15 355 24.0 301 -25 5 17.1 302 -25 15 19.0 304 -25 35 27.5 305 -25 45 32.8 306 -25 55 39.8 307 -25 65 32.4 308 -25 75 30.3 309 -25 85 29.2 310 -25 95 30.6 311 -25 105 29.5 312 -25 115 31.4 315 -25 145 36.4 316 -25 155 35.1 317 -25 165 37.3 318 -25 175 43.1 319 -25 185 43.6 320 -25 195 47.1 321 -25 205 51.2 322 -25 215 51.9 323 -25 225 49.5 324 -25 235 42.5 325 -25 245 40.8 326 -25 255 39.0 327 -25 265 35.7 328 -25 275 19.9 329 -25 285 25.0 332 -25 315 44.0 333 -25 325 41.9 334 -25 335 41.2 335 -25 345 34.2 336 -25 355 27.0 337 -35 5 35.1 338 -35 15 29.9 339 -35 25 35.9 340 -35 35 33.8 341 -35 45 34.2 342 -35 55 34.9 343 -35 65 38.0 344 -35 75 36.4 345 -35 85 34.7 346 -35 95 32.7 347 -35 105 31.9 348 -35 115 36.2 349 -35 125 38.9 350 -35 135 39.1 351 -35 145 40.8 352 -35 155 37.9 353 -35 165 36.1 354 -35 175 36.6 355 -35 185 37.3 356 -35 195 36.8 357 -35 205 39.3 358 -35 215 43.9 359 -35 225 48.7 360 -35 235 50.1 361 -35 245 44.5 362 -35 255 37.4 363 -35 265 29.0 364 -35 275 26.5 365 -35 285 30.6 366 -35 295 39.3 367 -35 305 36.6 368 -35 315 36.2 369 -35 325 37.7 370 -35 335 40.4 371 -35 345 44.1 372 -35 355 41.6 373 -45 5 36.1 374 -45 15 36.2 375 -45 25 32.6 376 -45 35 37.3 377 -45 45 37.0 378 -45 55 32.5 379 -45 65 33.9 380 -45 75 35.4 381 -45 85 33.1 382 -45 95 38.3 383 -45 105 36.8 384 -45 115 34.1 385 -45 125 38.8 386 -45 135 40.4 387 -45 145 42.0 388 -45 155 41.1 389 -45 165 36.6 390 -45 175 41.8 391 -45 185 38.5 392 -45 195 36.7 393 -45 205 35.1 394 -45 215 34.4 395 -45 225 44.4 396 -45 235 37.2 397 -45 245 33.5 398 -45 255 28.7 399 -45 265 24.6 400 -45 275 22.4 401 -45 285 24.3 402 -45 295 41.3 403 -45 305 38.2 404 -45 315 36.5 405 -45 325 38.8 406 -45 335 35.8 407 -45 345 36.2 408 -45 355 37.1 409 -55 10 38.6 410 -55 30 34.6 411 -55 50 23.4 412 -55 70 31.0 413 -55 90 41.8 414 -55 110 37.1 415 -55 130 40.6 416 -55 150 31.8 417 -55 170 27.0 418 -55 190 41.1 419 -55 210 33.1 420 -55 230 37.9 421 -55 250 39.5 422 -55 270 40.9 423 -55 290 47.8 424 -55 310 44.5 425 -55 330 28.3 426 -55 350 33.2 427 -65 10 42.5 428 -65 30 47.0 429 -65 50 38.5 430 -65 70 29.3 431 -65 90 33.8 432 -65 110 44.3 433 -65 130 38.6 434 -65 150 34.7 435 -65 170 39.1 437 -65 210 30.9 440 -65 270 39.1 441 -65 290 58.8 442 -65 310 28.3 443 -65 330 34.4 444 -65 350 35.8 449 -75 180 34.5 450 -75 220 55.0 453 -75 340 48.0