Altocumulus Frequency of Occurrence (%) March, April, May (1954 - 1997) Night, Ship Observations Only Global Average: 32.8 Zonal Averages 17 zones Lat.N Average 85 23.3 75 24.1 65 31.3 55 27.4 45 29.8 35 31.3 25 31.0 15 28.9 5 40.1 -5 37.0 -15 34.4 -25 36.2 -35 34.1 -45 31.2 -55 31.7 -65 27.1 -75 26.1 Grid Box Averages 374 filled boxes Box # Lat.N Lon.E Average 1 85 60 30.8 2 85 180 18.0 3 85 300 20.5 4 75 20 33.3 5 75 60 26.7 6 75 100 19.1 7 75 140 24.0 8 75 180 12.9 9 75 220 20.0 11 75 300 39.9 12 75 340 26.0 13 65 10 39.5 14 65 30 31.4 15 65 50 26.0 21 65 170 16.9 22 65 190 18.6 23 65 210 31.2 29 65 330 32.5 30 65 350 37.0 31 55 10 31.1 32 55 30 30.8 37 55 130 15.9 38 55 150 16.7 39 55 170 22.5 40 55 190 28.7 41 55 210 31.2 42 55 230 30.6 46 55 310 22.4 47 55 330 31.3 48 55 350 35.4 49 45 5 33.5 50 45 15 31.1 51 45 25 22.9 52 45 35 19.5 53 45 45 21.7 54 45 55 18.2 62 45 135 15.8 63 45 145 18.6 64 45 155 21.8 65 45 165 26.9 66 45 175 30.6 67 45 185 34.8 68 45 195 36.4 69 45 205 35.9 70 45 215 36.0 71 45 225 31.2 72 45 235 28.5 77 45 285 26.1 78 45 295 27.1 79 45 305 26.1 80 45 315 27.0 81 45 325 32.0 82 45 335 34.6 83 45 345 32.3 84 45 355 33.4 85 35 5 31.9 86 35 15 27.1 87 35 25 21.8 88 35 35 20.4 90 35 55 21.0 96 35 115 10.9 97 35 125 23.3 98 35 135 25.9 99 35 145 26.0 100 35 155 28.8 101 35 165 31.3 102 35 175 34.4 103 35 185 40.5 104 35 195 40.4 105 35 205 38.3 106 35 215 37.7 107 35 225 30.1 108 35 235 23.0 109 35 245 16.4 112 35 275 28.7 113 35 285 30.4 114 35 295 30.3 115 35 305 31.4 116 35 315 33.0 117 35 325 33.1 118 35 335 33.2 119 35 345 30.6 120 35 355 30.6 124 25 35 11.9 125 25 45 23.7 126 25 55 14.7 127 25 65 10.9 128 25 75 10.7 129 25 85 26.7 130 25 95 40.5 131 25 105 31.1 132 25 115 33.9 133 25 125 33.4 134 25 135 36.2 135 25 145 36.6 136 25 155 30.0 137 25 165 32.3 138 25 175 32.5 139 25 185 35.1 140 25 195 32.7 141 25 205 31.8 142 25 215 35.8 143 25 225 40.0 144 25 235 36.8 145 25 245 26.9 146 25 255 24.5 147 25 265 32.2 148 25 275 30.7 149 25 285 31.7 150 25 295 28.5 151 25 305 27.8 152 25 315 30.9 153 25 325 28.5 154 25 335 24.8 155 25 345 20.0 160 15 35 12.5 161 15 45 17.0 162 15 55 11.3 163 15 65 11.5 164 15 75 19.0 165 15 85 25.1 166 15 95 23.1 167 15 105 27.8 168 15 115 21.7 169 15 125 28.8 170 15 135 30.1 171 15 145 32.5 172 15 155 26.6 173 15 165 26.2 174 15 175 29.6 175 15 185 31.8 176 15 195 35.0 177 15 205 36.2 178 15 215 41.9 179 15 225 48.8 180 15 235 45.5 181 15 245 33.4 182 15 255 25.5 183 15 265 27.9 184 15 275 32.5 185 15 285 29.3 186 15 295 26.7 187 15 305 26.5 188 15 315 30.4 189 15 325 26.3 190 15 335 22.6 191 15 345 17.3 193 5 5 45.1 197 5 45 17.2 198 5 55 18.9 199 5 65 19.4 200 5 75 30.0 201 5 85 41.4 202 5 95 50.9 203 5 105 33.1 204 5 115 34.6 205 5 125 41.6 206 5 135 45.2 207 5 145 47.4 208 5 155 48.2 209 5 165 45.6 210 5 175 44.0 211 5 185 46.1 212 5 195 44.3 213 5 205 44.6 214 5 215 43.9 215 5 225 48.4 216 5 235 43.1 217 5 245 36.4 218 5 255 35.7 219 5 265 40.8 220 5 275 48.1 221 5 285 41.7 223 5 305 34.3 224 5 315 43.8 225 5 325 39.7 226 5 335 34.3 227 5 345 32.9 228 5 355 42.0 229 -5 5 41.8 230 -5 15 29.5 232 -5 35 19.7 233 -5 45 27.4 234 -5 55 23.5 235 -5 65 29.5 236 -5 75 37.0 237 -5 85 44.9 238 -5 95 48.7 239 -5 105 48.6 240 -5 115 45.3 241 -5 125 41.9 242 -5 135 43.1 243 -5 145 53.6 244 -5 155 49.0 245 -5 165 43.7 246 -5 175 45.6 247 -5 185 40.8 248 -5 195 33.5 249 -5 205 28.5 250 -5 215 30.5 251 -5 225 26.3 252 -5 235 31.5 253 -5 245 31.9 254 -5 255 35.7 255 -5 265 35.9 256 -5 275 49.5 257 -5 285 40.8 260 -5 315 54.7 261 -5 325 40.6 262 -5 335 28.7 263 -5 345 25.3 264 -5 355 29.1 265 -15 5 28.8 266 -15 15 35.9 268 -15 35 23.8 269 -15 45 29.7 270 -15 55 31.8 271 -15 65 31.8 272 -15 75 30.3 273 -15 85 36.9 274 -15 95 44.8 275 -15 105 34.8 276 -15 115 26.3 277 -15 125 25.4 278 -15 135 34.5 279 -15 145 39.8 280 -15 155 38.9 281 -15 165 39.6 282 -15 175 44.9 283 -15 185 48.9 284 -15 195 37.3 285 -15 205 32.3 286 -15 215 30.2 287 -15 225 29.2 288 -15 235 27.9 289 -15 245 31.9 290 -15 255 36.2 291 -15 265 37.5 292 -15 275 37.1 293 -15 285 39.3 297 -15 325 36.8 298 -15 335 28.3 299 -15 345 30.1 300 -15 355 31.0 301 -25 5 30.0 302 -25 15 22.9 304 -25 35 24.0 305 -25 45 31.7 306 -25 55 37.7 307 -25 65 35.8 308 -25 75 36.3 309 -25 85 37.0 310 -25 95 42.8 311 -25 105 35.6 312 -25 115 26.5 315 -25 145 36.9 316 -25 155 29.8 317 -25 165 37.0 318 -25 175 41.1 319 -25 185 44.6 320 -25 195 42.3 321 -25 205 39.2 322 -25 215 36.0 323 -25 225 35.4 324 -25 235 35.0 325 -25 245 32.1 326 -25 255 38.2 327 -25 265 38.2 328 -25 275 36.8 329 -25 285 38.0 332 -25 315 44.4 333 -25 325 39.0 334 -25 335 36.0 335 -25 345 32.4 336 -25 355 34.7 337 -35 5 38.2 338 -35 15 26.1 339 -35 25 27.7 340 -35 35 26.4 341 -35 45 32.3 342 -35 55 38.5 343 -35 65 40.5 344 -35 75 34.9 345 -35 85 35.9 346 -35 95 37.6 347 -35 105 32.9 348 -35 115 32.7 349 -35 125 35.7 350 -35 135 36.5 351 -35 145 36.4 352 -35 155 32.6 353 -35 165 32.7 354 -35 175 36.2 355 -35 185 37.6 356 -35 195 38.6 357 -35 205 35.0 358 -35 215 35.1 359 -35 225 36.2 360 -35 235 38.2 361 -35 245 34.9 362 -35 255 31.9 363 -35 265 31.6 364 -35 275 32.7 365 -35 285 24.0 367 -35 305 27.6 368 -35 315 32.8 369 -35 325 30.9 370 -35 335 28.1 371 -35 345 38.2 372 -35 355 39.2 373 -45 5 23.8 374 -45 15 40.0 375 -45 25 50.3 376 -45 35 32.1 377 -45 45 38.3 378 -45 55 24.9 379 -45 65 28.9 380 -45 75 29.6 381 -45 85 37.6 382 -45 95 35.7 383 -45 105 31.2 386 -45 135 33.5 387 -45 145 32.9 388 -45 155 30.1 389 -45 165 25.4 390 -45 175 31.3 391 -45 185 35.1 392 -45 195 36.2 393 -45 205 33.0 394 -45 215 29.4 396 -45 235 42.9 397 -45 245 18.4 398 -45 255 17.6 399 -45 265 28.3 400 -45 275 22.5 401 -45 285 24.0 402 -45 295 25.6 403 -45 305 27.5 404 -45 315 31.6 405 -45 325 26.0 407 -45 345 36.1 409 -55 10 35.7 410 -55 30 33.3 411 -55 50 24.2 412 -55 70 30.0 413 -55 90 25.7 414 -55 110 18.9 416 -55 150 36.7 417 -55 170 31.0 418 -55 190 40.7 419 -55 210 29.6 422 -55 270 33.9 423 -55 290 35.1 424 -55 310 34.4 425 -55 330 31.9 426 -55 350 35.6 427 -65 10 31.6 428 -65 30 30.7 429 -65 50 28.0 430 -65 70 15.3 431 -65 90 25.7 432 -65 110 30.0 433 -65 130 24.0 434 -65 150 20.1 435 -65 170 26.2 436 -65 190 21.7 437 -65 210 22.9 440 -65 270 26.4 441 -65 290 28.4 442 -65 310 34.4 444 -65 350 38.1 449 -75 180 22.8 450 -75 220 19.2 453 -75 340 40.4