Altostratus Amount-When-Present (%) March, April, May (1954 - 1997) , Ship Observations Only Global Average: 58.8 Zonal Averages 17 zones Lat.N Average 85 78.8 75 67.6 65 69.2 55 67.5 45 63.5 35 61.5 25 51.2 15 46.4 5 54.8 -5 51.6 -15 51.2 -25 54.4 -35 61.0 -45 63.5 -55 73.3 -65 77.6 -75 77.9 Grid Box Averages 341 filled boxes Box # Lat.N Lon.E Average 1 85 60 80.4 2 85 180 79.6 3 85 300 73.7 4 75 20 64.4 5 75 60 62.1 8 75 180 77.2 12 75 340 73.8 13 65 10 66.8 14 65 30 57.9 15 65 50 52.0 21 65 170 63.9 22 65 190 65.7 23 65 210 73.8 29 65 330 82.3 30 65 350 66.6 31 55 10 71.5 32 55 30 57.4 38 55 150 61.5 39 55 170 64.5 40 55 190 62.5 41 55 210 60.4 42 55 230 60.3 46 55 310 81.2 47 55 330 76.4 48 55 350 71.8 49 45 5 61.0 50 45 15 62.0 51 45 25 65.2 52 45 35 59.7 53 45 45 43.5 54 45 55 38.3 62 45 135 63.3 63 45 145 59.7 64 45 155 58.1 65 45 165 60.0 66 45 175 60.5 67 45 185 60.1 68 45 195 59.0 69 45 205 59.5 70 45 215 59.6 71 45 225 59.6 72 45 235 60.1 77 45 285 63.6 78 45 295 69.6 79 45 305 75.1 80 45 315 76.2 81 45 325 73.8 82 45 335 72.3 83 45 345 69.4 84 45 355 65.3 85 35 5 59.8 86 35 15 59.1 87 35 25 59.4 88 35 35 59.5 96 35 115 66.1 97 35 125 69.9 98 35 135 68.3 99 35 145 59.6 100 35 155 59.9 101 35 165 64.5 102 35 175 58.2 103 35 185 61.7 104 35 195 58.9 105 35 205 61.1 106 35 215 58.2 107 35 225 58.7 108 35 235 51.8 109 35 245 52.8 112 35 275 54.7 113 35 285 61.6 114 35 295 67.5 115 35 305 67.9 116 35 315 67.2 117 35 325 63.1 118 35 335 60.2 119 35 345 56.2 120 35 355 53.5 124 25 35 55.0 125 25 45 72.4 126 25 55 58.3 127 25 65 42.1 129 25 85 39.2 132 25 115 66.9 133 25 125 57.0 134 25 135 49.9 135 25 145 44.6 136 25 155 52.4 137 25 165 46.8 138 25 175 46.1 139 25 185 46.6 140 25 195 49.4 141 25 205 52.7 142 25 215 56.2 143 25 225 56.5 144 25 235 55.5 145 25 245 49.7 146 25 255 42.2 147 25 265 54.9 148 25 275 46.6 149 25 285 49.5 150 25 295 50.0 151 25 305 52.5 152 25 315 50.2 153 25 325 46.1 154 25 335 50.6 155 25 345 51.6 160 15 35 52.1 161 15 45 46.3 162 15 55 37.8 163 15 65 34.8 164 15 75 41.4 165 15 85 41.3 166 15 95 44.5 167 15 105 53.7 168 15 115 34.4 169 15 125 32.5 170 15 135 31.8 171 15 145 29.8 172 15 155 34.7 173 15 165 47.7 174 15 175 47.2 175 15 185 50.4 176 15 195 55.8 177 15 205 52.6 178 15 215 53.4 179 15 225 62.8 180 15 235 62.5 181 15 245 49.0 182 15 255 44.4 183 15 265 50.9 184 15 275 45.0 185 15 285 45.6 186 15 295 40.0 187 15 305 42.9 188 15 315 43.5 189 15 325 52.6 190 15 335 59.4 191 15 345 63.2 193 5 5 66.3 197 5 45 36.2 198 5 55 44.6 199 5 65 46.9 200 5 75 55.2 201 5 85 58.9 202 5 95 63.1 203 5 105 47.3 204 5 115 44.2 205 5 125 50.0 206 5 135 48.6 207 5 145 51.5 208 5 155 51.8 209 5 165 57.1 210 5 175 53.8 211 5 185 45.8 212 5 195 57.2 213 5 205 59.0 214 5 215 54.2 215 5 225 53.0 216 5 235 51.9 217 5 245 58.4 218 5 255 44.1 219 5 265 53.8 220 5 275 59.2 221 5 285 63.3 223 5 305 51.1 224 5 315 52.9 225 5 325 61.9 226 5 335 59.3 227 5 345 67.0 228 5 355 63.6 229 -5 5 51.9 230 -5 15 46.5 233 -5 45 47.2 234 -5 55 34.6 235 -5 65 54.3 236 -5 75 57.8 237 -5 85 62.5 238 -5 95 62.7 239 -5 105 55.8 240 -5 115 55.0 241 -5 125 52.8 242 -5 135 62.5 243 -5 145 59.4 244 -5 155 59.2 245 -5 165 55.5 246 -5 175 48.9 247 -5 185 57.0 248 -5 195 47.5 249 -5 205 41.4 250 -5 215 36.9 251 -5 225 38.1 252 -5 235 40.5 253 -5 245 48.6 254 -5 255 48.8 255 -5 265 49.1 256 -5 275 51.2 257 -5 285 47.6 260 -5 315 54.3 261 -5 325 51.6 262 -5 335 37.6 263 -5 345 44.1 264 -5 355 46.2 265 -15 5 55.9 266 -15 15 57.3 268 -15 35 38.5 269 -15 45 46.7 270 -15 55 52.4 271 -15 65 49.2 272 -15 75 49.6 273 -15 85 53.7 274 -15 95 54.4 275 -15 105 42.8 276 -15 115 51.0 277 -15 125 49.5 278 -15 135 57.6 279 -15 145 57.8 280 -15 155 53.7 281 -15 165 55.4 282 -15 175 57.4 283 -15 185 62.5 284 -15 195 60.0 285 -15 205 56.9 286 -15 215 48.9 287 -15 225 47.8 288 -15 235 43.1 289 -15 245 41.8 290 -15 255 52.1 291 -15 265 40.4 292 -15 275 46.7 293 -15 285 53.6 297 -15 325 43.6 298 -15 335 38.3 299 -15 345 38.4 300 -15 355 47.6 301 -25 5 51.0 302 -25 15 49.9 304 -25 35 50.2 305 -25 45 44.7 306 -25 55 56.0 307 -25 65 46.4 308 -25 75 55.7 309 -25 85 53.2 310 -25 95 58.6 311 -25 105 54.2 312 -25 115 45.5 315 -25 145 48.4 316 -25 155 51.3 317 -25 165 52.2 318 -25 175 59.9 319 -25 185 61.5 320 -25 195 70.0 321 -25 205 61.9 322 -25 215 67.5 323 -25 225 59.3 324 -25 235 57.4 325 -25 245 66.2 327 -25 265 49.2 328 -25 275 42.5 329 -25 285 69.6 332 -25 315 47.1 333 -25 325 46.2 334 -25 335 45.8 335 -25 345 45.9 336 -25 355 43.5 337 -35 5 63.4 338 -35 15 53.1 339 -35 25 57.3 340 -35 35 55.9 341 -35 45 54.1 342 -35 55 59.2 343 -35 65 63.2 344 -35 75 59.5 345 -35 85 60.0 346 -35 95 63.4 347 -35 105 62.2 348 -35 115 60.2 349 -35 125 65.0 350 -35 135 60.3 351 -35 145 57.5 352 -35 155 58.7 353 -35 165 63.5 354 -35 175 57.9 355 -35 185 65.8 356 -35 195 68.6 357 -35 205 72.0 358 -35 215 75.1 359 -35 225 75.3 360 -35 235 71.2 363 -35 265 59.9 364 -35 275 48.0 365 -35 285 54.3 367 -35 305 51.6 368 -35 315 54.1 369 -35 325 62.6 370 -35 335 61.1 371 -35 345 55.2 372 -35 355 54.4 376 -45 35 80.6 377 -45 45 84.3 378 -45 55 73.3 379 -45 65 63.1 380 -45 75 61.9 386 -45 135 77.6 387 -45 145 62.2 388 -45 155 71.6 389 -45 165 67.3 390 -45 175 57.8 391 -45 185 59.8 392 -45 195 68.0 393 -45 205 66.3 396 -45 235 57.2 397 -45 245 64.8 398 -45 255 53.5 399 -45 265 51.8 400 -45 275 50.2 401 -45 285 66.4 402 -45 295 44.2 403 -45 305 55.7 404 -45 315 67.0 405 -45 325 53.7 409 -55 10 81.8 410 -55 30 90.0 411 -55 50 69.6 412 -55 70 75.2 413 -55 90 82.2 417 -55 170 70.9 422 -55 270 73.5 423 -55 290 62.7 424 -55 310 69.6 425 -55 330 60.5 426 -55 350 71.6 427 -65 10 80.7 428 -65 30 83.0 429 -65 50 73.3 430 -65 70 53.0 433 -65 130 83.2 434 -65 150 79.0 435 -65 170 78.7 441 -65 290 80.8 442 -65 310 77.3 449 -75 180 77.9