Altocumulus Average Cloud Amount (%) March, April, May (1954 - 1997) Night, Ship Observations Only Global Average: 16.2 Zonal Averages 17 zones Lat.N Average 85 11.7 75 12.1 65 16.1 55 13.5 45 14.4 35 15.7 25 13.8 15 12.5 5 18.9 -5 16.9 -15 15.4 -25 16.8 -35 16.8 -45 18.2 -55 19.1 -65 17.4 -75 15.0 Grid Box Averages 374 filled boxes Box # Lat.N Lon.E Average 1 85 60 15.5 2 85 180 9.9 3 85 300 9.0 4 75 20 17.6 5 75 60 14.6 6 75 100 7.7 7 75 140 11.7 8 75 180 6.8 9 75 220 10.8 11 75 300 14.9 12 75 340 12.4 13 65 10 19.7 14 65 30 15.9 15 65 50 12.1 21 65 170 8.5 22 65 190 10.1 23 65 210 12.4 29 65 330 17.7 30 65 350 18.6 31 55 10 15.6 32 55 30 16.7 37 55 130 9.2 38 55 150 8.0 39 55 170 10.9 40 55 190 12.7 41 55 210 14.3 42 55 230 13.1 46 55 310 13.2 47 55 330 17.1 48 55 350 17.0 49 45 5 15.4 50 45 15 14.4 51 45 25 12.4 52 45 35 10.1 53 45 45 11.4 54 45 55 9.3 62 45 135 8.2 63 45 145 8.9 64 45 155 10.1 65 45 165 12.5 66 45 175 13.9 67 45 185 16.4 68 45 195 16.1 69 45 205 16.2 70 45 215 15.9 71 45 225 14.1 72 45 235 12.8 77 45 285 13.7 78 45 295 14.0 79 45 305 13.6 80 45 315 15.6 81 45 325 17.1 82 45 335 18.3 83 45 345 16.1 84 45 355 15.8 85 35 5 14.9 86 35 15 12.5 87 35 25 10.2 88 35 35 8.7 90 35 55 14.9 96 35 115 4.8 97 35 125 13.5 98 35 135 14.1 99 35 145 12.4 100 35 155 14.2 101 35 165 17.1 102 35 175 17.7 103 35 185 21.1 104 35 195 20.0 105 35 205 19.0 106 35 215 19.0 107 35 225 15.0 108 35 235 10.4 109 35 245 7.8 112 35 275 13.3 113 35 285 15.5 114 35 295 15.9 115 35 305 16.0 116 35 315 17.1 117 35 325 16.7 118 35 335 16.7 119 35 345 14.1 120 35 355 13.1 124 25 35 5.3 125 25 45 12.4 126 25 55 6.9 127 25 65 4.4 128 25 75 4.5 129 25 85 11.0 130 25 95 15.4 131 25 105 15.6 132 25 115 18.8 133 25 125 17.0 134 25 135 15.5 135 25 145 14.9 136 25 155 13.3 137 25 165 13.8 138 25 175 13.3 139 25 185 13.8 140 25 195 13.5 141 25 205 14.0 142 25 215 17.2 143 25 225 21.4 144 25 235 17.4 145 25 245 11.9 146 25 255 10.5 147 25 265 15.4 148 25 275 12.3 149 25 285 13.6 150 25 295 12.4 151 25 305 12.1 152 25 315 13.8 153 25 325 12.3 154 25 335 11.4 155 25 345 8.4 160 15 35 6.0 161 15 45 7.6 162 15 55 4.0 163 15 65 3.4 164 15 75 7.5 165 15 85 9.9 166 15 95 8.9 167 15 105 13.3 168 15 115 7.7 169 15 125 9.5 170 15 135 9.0 171 15 145 9.1 172 15 155 10.3 173 15 165 11.6 174 15 175 12.2 175 15 185 12.8 176 15 195 15.8 177 15 205 17.4 178 15 215 20.5 179 15 225 26.7 180 15 235 25.3 181 15 245 16.5 182 15 255 10.6 183 15 265 12.3 184 15 275 12.8 185 15 285 12.1 186 15 295 10.9 187 15 305 10.9 188 15 315 14.0 189 15 325 12.6 190 15 335 11.3 191 15 345 9.1 193 5 5 24.7 197 5 45 6.7 198 5 55 7.4 199 5 65 7.8 200 5 75 13.6 201 5 85 19.2 202 5 95 27.1 203 5 105 14.8 204 5 115 15.1 205 5 125 16.4 206 5 135 20.7 207 5 145 19.3 208 5 155 21.7 209 5 165 21.2 210 5 175 20.4 211 5 185 21.7 212 5 195 23.9 213 5 205 24.1 214 5 215 18.6 215 5 225 20.8 216 5 235 15.3 217 5 245 17.1 218 5 255 14.6 219 5 265 19.3 220 5 275 24.5 221 5 285 21.0 223 5 305 16.5 224 5 315 24.3 225 5 325 20.6 226 5 335 19.1 227 5 345 18.1 228 5 355 22.1 229 -5 5 21.8 230 -5 15 15.7 232 -5 35 8.1 233 -5 45 11.6 234 -5 55 9.4 235 -5 65 12.6 236 -5 75 16.8 237 -5 85 21.2 238 -5 95 24.1 239 -5 105 25.1 240 -5 115 23.3 241 -5 125 19.8 242 -5 135 23.8 243 -5 145 29.1 244 -5 155 23.2 245 -5 165 22.4 246 -5 175 18.3 247 -5 185 16.8 248 -5 195 13.9 249 -5 205 9.3 250 -5 215 12.1 251 -5 225 8.7 252 -5 235 12.2 253 -5 245 13.9 254 -5 255 16.8 255 -5 265 16.2 256 -5 275 27.1 257 -5 285 21.4 260 -5 315 29.2 261 -5 325 18.9 262 -5 335 12.5 263 -5 345 11.1 264 -5 355 12.9 265 -15 5 14.6 266 -15 15 27.8 268 -15 35 9.6 269 -15 45 12.4 270 -15 55 13.1 271 -15 65 13.9 272 -15 75 14.1 273 -15 85 16.1 274 -15 95 19.1 275 -15 105 15.0 276 -15 115 10.7 277 -15 125 11.9 278 -15 135 18.6 279 -15 145 20.1 280 -15 155 17.7 281 -15 165 18.2 282 -15 175 21.3 283 -15 185 22.7 284 -15 195 18.2 285 -15 205 13.0 286 -15 215 10.8 287 -15 225 10.3 288 -15 235 11.5 289 -15 245 13.4 290 -15 255 16.8 291 -15 265 17.6 292 -15 275 19.2 293 -15 285 19.3 297 -15 325 15.1 298 -15 335 10.7 299 -15 345 12.6 300 -15 355 14.6 301 -25 5 13.9 302 -25 15 11.2 304 -25 35 9.9 305 -25 45 12.9 306 -25 55 16.7 307 -25 65 15.1 308 -25 75 15.7 309 -25 85 16.9 310 -25 95 18.6 311 -25 105 16.4 312 -25 115 12.0 315 -25 145 18.5 316 -25 155 12.9 317 -25 165 16.4 318 -25 175 19.0 319 -25 185 21.2 320 -25 195 23.9 321 -25 205 22.1 322 -25 215 18.5 323 -25 225 14.7 324 -25 235 16.1 325 -25 245 13.6 326 -25 255 18.5 327 -25 265 17.6 328 -25 275 16.0 329 -25 285 22.3 332 -25 315 21.0 333 -25 325 17.3 334 -25 335 15.7 335 -25 345 14.2 336 -25 355 16.4 337 -35 5 19.0 338 -35 15 11.2 339 -35 25 12.7 340 -35 35 12.0 341 -35 45 14.9 342 -35 55 19.6 343 -35 65 20.3 344 -35 75 18.4 345 -35 85 18.7 346 -35 95 18.9 347 -35 105 16.8 348 -35 115 15.2 349 -35 125 18.1 350 -35 135 19.0 351 -35 145 17.4 352 -35 155 14.9 353 -35 165 15.2 354 -35 175 15.8 355 -35 185 17.9 356 -35 195 18.2 357 -35 205 18.6 358 -35 215 19.9 359 -35 225 20.4 360 -35 235 18.2 361 -35 245 13.6 362 -35 255 16.6 363 -35 265 16.4 364 -35 275 15.8 365 -35 285 10.8 367 -35 305 12.8 368 -35 315 17.0 369 -35 325 15.8 370 -35 335 14.5 371 -35 345 20.6 372 -35 355 18.9 373 -45 5 14.9 374 -45 15 26.1 375 -45 25 32.5 376 -45 35 24.4 377 -45 45 27.8 378 -45 55 15.9 379 -45 65 19.0 380 -45 75 15.6 381 -45 85 26.8 382 -45 95 19.0 383 -45 105 16.4 386 -45 135 22.4 387 -45 145 17.3 388 -45 155 14.9 389 -45 165 14.1 390 -45 175 15.0 391 -45 185 19.3 392 -45 195 19.1 393 -45 205 16.6 394 -45 215 16.9 396 -45 235 23.6 397 -45 245 8.0 398 -45 255 11.1 399 -45 265 15.7 400 -45 275 11.8 401 -45 285 12.3 402 -45 295 12.7 403 -45 305 14.9 404 -45 315 15.7 405 -45 325 15.5 407 -45 345 21.6 409 -55 10 23.1 410 -55 30 21.8 411 -55 50 14.5 412 -55 70 18.3 413 -55 90 13.4 414 -55 110 14.3 416 -55 150 21.4 417 -55 170 24.6 418 -55 190 20.2 419 -55 210 12.8 422 -55 270 18.0 423 -55 290 17.6 424 -55 310 20.3 425 -55 330 21.3 426 -55 350 24.6 427 -65 10 19.9 428 -65 30 15.9 429 -65 50 19.2 430 -65 70 10.5 431 -65 90 16.4 432 -65 110 18.1 433 -65 130 16.1 434 -65 150 13.0 435 -65 170 17.6 436 -65 190 12.4 437 -65 210 18.0 440 -65 270 16.8 441 -65 290 15.0 442 -65 310 25.8 444 -65 350 23.3 449 -75 180 14.4 450 -75 220 10.9 453 -75 340 21.4