Altostratus Amount-When-Present (%) March, April, May (1954 - 1997) Day, Ship Observations Only Global Average: 56.7 Zonal Averages 17 zones Lat.N Average 85 78.2 75 66.9 65 70.3 55 66.6 45 62.0 35 60.2 25 48.6 15 44.0 5 53.6 -5 49.9 -15 48.5 -25 52.3 -35 58.5 -45 59.6 -55 70.1 -65 76.2 -75 75.0 Grid Box Averages 327 filled boxes Box # Lat.N Lon.E Average 2 85 180 78.2 4 75 20 64.3 5 75 60 61.4 8 75 180 76.5 12 75 340 71.2 13 65 10 67.6 14 65 30 57.1 15 65 50 52.7 21 65 170 63.2 22 65 190 66.2 29 65 330 83.9 30 65 350 68.8 31 55 10 73.4 32 55 30 60.0 38 55 150 61.1 39 55 170 62.6 40 55 190 60.7 41 55 210 58.8 42 55 230 60.4 46 55 310 82.2 47 55 330 75.0 48 55 350 72.0 49 45 5 61.1 50 45 15 63.4 51 45 25 66.8 52 45 35 63.2 53 45 45 45.0 54 45 55 36.5 62 45 135 62.8 63 45 145 60.1 64 45 155 55.8 65 45 165 56.4 66 45 175 57.0 67 45 185 57.1 68 45 195 57.5 69 45 205 57.7 70 45 215 57.8 71 45 225 57.5 72 45 235 58.8 77 45 285 65.2 78 45 295 73.6 79 45 305 74.8 80 45 315 75.2 81 45 325 72.5 82 45 335 70.8 83 45 345 68.2 84 45 355 65.3 85 35 5 59.1 86 35 15 61.4 87 35 25 61.0 88 35 35 58.9 96 35 115 65.6 97 35 125 70.2 98 35 135 66.5 99 35 145 59.0 100 35 155 57.7 101 35 165 61.0 102 35 175 57.1 103 35 185 58.8 104 35 195 58.0 105 35 205 58.4 106 35 215 57.5 107 35 225 55.2 108 35 235 49.8 109 35 245 54.2 112 35 275 59.0 113 35 285 63.4 114 35 295 67.3 115 35 305 66.5 116 35 315 64.6 117 35 325 61.6 118 35 335 58.7 119 35 345 54.7 120 35 355 53.5 124 25 35 55.8 125 25 45 74.7 126 25 55 57.4 127 25 65 38.0 129 25 85 33.6 132 25 115 66.3 133 25 125 56.3 134 25 135 47.2 135 25 145 41.7 136 25 155 48.0 137 25 165 43.7 138 25 175 42.0 139 25 185 42.8 140 25 195 47.9 141 25 205 48.5 142 25 215 51.7 143 25 225 51.7 144 25 235 50.4 145 25 245 46.1 146 25 255 40.2 147 25 265 56.6 148 25 275 47.0 149 25 285 48.0 150 25 295 49.2 151 25 305 50.3 152 25 315 47.7 153 25 325 42.4 154 25 335 49.6 155 25 345 50.7 160 15 35 50.4 161 15 45 44.1 162 15 55 35.2 163 15 65 30.9 164 15 75 37.3 165 15 85 40.8 166 15 95 42.7 167 15 105 53.9 168 15 115 33.0 169 15 125 31.1 170 15 135 31.9 171 15 145 28.8 172 15 155 35.0 173 15 165 47.3 174 15 175 43.5 175 15 185 47.5 176 15 195 53.3 177 15 205 48.1 178 15 215 48.2 179 15 225 56.3 180 15 235 54.3 181 15 245 45.7 182 15 255 42.2 183 15 265 49.7 184 15 275 43.5 185 15 285 45.4 186 15 295 39.5 187 15 305 40.8 188 15 315 42.2 189 15 325 51.1 190 15 335 59.4 191 15 345 62.5 193 5 5 68.1 197 5 45 33.3 198 5 55 41.0 199 5 65 46.1 200 5 75 54.1 201 5 85 58.4 202 5 95 62.9 203 5 105 45.3 204 5 115 42.9 205 5 125 45.9 206 5 135 53.3 207 5 145 47.5 208 5 155 49.1 209 5 165 51.0 210 5 175 54.7 211 5 185 49.9 212 5 195 54.1 213 5 205 54.8 214 5 215 53.1 215 5 225 46.9 216 5 235 49.2 217 5 245 52.7 218 5 255 42.6 219 5 265 53.8 220 5 275 60.1 221 5 285 67.8 223 5 305 48.2 224 5 315 51.0 225 5 325 59.7 226 5 335 59.4 227 5 345 68.2 228 5 355 66.4 229 -5 5 49.6 230 -5 15 44.9 233 -5 45 44.5 234 -5 55 35.1 235 -5 65 51.6 236 -5 75 57.1 237 -5 85 63.9 238 -5 95 60.5 239 -5 105 58.8 240 -5 115 52.1 241 -5 125 47.4 242 -5 135 60.8 243 -5 145 59.6 244 -5 155 56.3 245 -5 165 53.1 246 -5 175 52.9 247 -5 185 52.6 248 -5 195 44.8 249 -5 205 38.3 250 -5 215 36.3 251 -5 225 38.1 252 -5 235 38.4 253 -5 245 47.4 254 -5 255 45.3 255 -5 265 46.0 256 -5 275 45.0 257 -5 285 54.2 260 -5 315 52.6 261 -5 325 49.5 262 -5 335 39.5 263 -5 345 42.5 264 -5 355 43.9 265 -15 5 48.2 266 -15 15 59.9 268 -15 35 38.3 269 -15 45 44.6 270 -15 55 48.0 271 -15 65 47.4 272 -15 75 43.1 273 -15 85 51.2 274 -15 95 53.7 275 -15 105 42.1 276 -15 115 47.9 277 -15 125 50.1 278 -15 135 59.3 279 -15 145 52.3 280 -15 155 51.0 281 -15 165 52.8 282 -15 175 55.5 283 -15 185 62.3 284 -15 195 60.7 285 -15 205 54.2 286 -15 215 48.0 287 -15 225 41.8 288 -15 235 37.0 289 -15 245 42.2 290 -15 255 42.2 292 -15 275 36.6 293 -15 285 54.0 297 -15 325 41.9 298 -15 335 35.2 299 -15 345 32.4 300 -15 355 40.7 301 -25 5 45.4 302 -25 15 50.2 304 -25 35 46.5 305 -25 45 43.4 306 -25 55 51.8 307 -25 65 45.0 308 -25 75 47.9 309 -25 85 45.2 310 -25 95 53.4 311 -25 105 50.1 312 -25 115 42.3 316 -25 155 49.7 317 -25 165 48.0 318 -25 175 57.1 319 -25 185 57.1 320 -25 195 67.3 321 -25 205 70.4 322 -25 215 69.7 323 -25 225 61.6 324 -25 235 58.0 325 -25 245 61.3 327 -25 265 48.8 328 -25 275 40.7 329 -25 285 66.8 332 -25 315 47.0 333 -25 325 45.7 334 -25 335 47.7 335 -25 345 45.1 336 -25 355 40.0 337 -35 5 57.9 338 -35 15 51.0 339 -35 25 54.2 340 -35 35 53.8 341 -35 45 51.4 342 -35 55 53.6 343 -35 65 62.5 344 -35 75 55.1 345 -35 85 51.7 346 -35 95 58.9 347 -35 105 62.9 348 -35 115 56.9 349 -35 125 61.1 350 -35 135 58.1 351 -35 145 56.4 352 -35 155 58.0 353 -35 165 62.8 354 -35 175 57.1 355 -35 185 64.6 356 -35 195 69.6 357 -35 205 68.4 358 -35 215 73.3 359 -35 225 70.2 360 -35 235 69.7 363 -35 265 61.3 364 -35 275 46.0 365 -35 285 60.3 367 -35 305 49.5 368 -35 315 57.1 369 -35 325 58.0 370 -35 335 58.3 371 -35 345 52.9 372 -35 355 47.8 377 -45 45 76.9 380 -45 75 58.8 386 -45 135 77.8 387 -45 145 62.2 388 -45 155 69.3 389 -45 165 63.9 390 -45 175 51.9 391 -45 185 61.9 392 -45 195 66.5 393 -45 205 65.0 396 -45 235 59.0 397 -45 245 67.5 398 -45 255 50.6 399 -45 265 51.1 400 -45 275 48.6 401 -45 285 64.7 402 -45 295 44.5 403 -45 305 48.5 404 -45 315 61.4 405 -45 325 53.5 410 -55 30 89.1 411 -55 50 66.2 412 -55 70 73.5 417 -55 170 66.4 423 -55 290 64.0 424 -55 310 68.3 425 -55 330 62.6 427 -65 10 81.7 429 -65 50 69.9 430 -65 70 51.6 433 -65 130 81.7 434 -65 150 79.5 441 -65 290 79.8 442 -65 310 79.0 449 -75 180 75.0