High Level (Cirriform) Frequency of Occurrence (%) August (1954 - 1997) Night, Ship Observations Only Global Average: 27.7 Zonal Averages 15 zones Lat.N Average 85 54.3 75 43.3 65 43.0 55 41.0 45 36.4 35 28.7 25 30.0 15 37.4 5 40.5 -5 27.3 -15 17.3 -25 16.8 -35 19.3 -45 21.4 -55 19.5 Grid Box Averages 306 filled boxes Box # Lat.N Lon.E Average 1 85 60 49.9 2 85 180 58.3 3 85 300 54.7 4 75 20 39.6 5 75 60 36.4 6 75 100 38.1 7 75 140 41.3 8 75 180 44.4 9 75 220 52.6 10 75 260 48.6 11 75 300 48.5 12 75 340 41.8 13 65 10 40.0 14 65 30 36.0 15 65 50 36.7 21 65 170 33.7 22 65 190 43.1 23 65 210 43.8 25 65 250 49.1 26 65 270 50.7 27 65 290 50.3 28 65 310 49.9 29 65 330 40.5 30 65 350 39.8 31 55 10 39.2 32 55 30 43.5 38 55 150 31.5 39 55 170 38.3 40 55 190 47.5 41 55 210 44.3 42 55 230 38.6 44 55 270 49.5 45 55 290 45.4 46 55 310 41.4 47 55 330 37.9 48 55 350 43.8 49 45 5 27.6 50 45 15 25.3 51 45 25 11.9 52 45 35 12.6 62 45 135 36.2 63 45 145 36.8 64 45 155 41.0 65 45 165 41.7 66 45 175 44.0 67 45 185 47.8 68 45 195 48.7 69 45 205 45.9 70 45 215 35.8 71 45 225 25.5 72 45 235 25.2 77 45 285 42.4 78 45 295 44.9 79 45 305 36.1 80 45 315 33.3 81 45 325 31.6 82 45 335 27.6 83 45 345 31.2 84 45 355 33.1 85 35 5 19.5 86 35 15 12.9 87 35 25 4.4 88 35 35 3.0 97 35 125 34.4 98 35 135 43.1 99 35 145 43.8 100 35 155 38.7 101 35 165 38.9 102 35 175 40.3 103 35 185 40.6 104 35 195 41.1 105 35 205 32.4 106 35 215 21.5 107 35 225 17.0 108 35 235 14.1 109 35 245 15.8 112 35 275 48.0 113 35 285 48.3 114 35 295 37.2 115 35 305 28.1 116 35 315 24.4 117 35 325 18.9 118 35 335 16.3 119 35 345 12.9 120 35 355 16.5 124 25 35 12.4 125 25 45 5.5 126 25 55 13.2 127 25 65 23.8 132 25 115 42.1 133 25 125 38.8 134 25 135 46.9 135 25 145 43.2 136 25 155 41.5 137 25 165 36.0 138 25 175 39.5 139 25 185 37.1 140 25 195 35.2 141 25 205 22.1 142 25 215 18.5 143 25 225 23.1 144 25 235 19.8 145 25 245 28.0 146 25 255 40.7 147 25 265 45.5 148 25 275 50.9 149 25 285 47.7 150 25 295 30.1 151 25 305 19.2 152 25 315 13.8 153 25 325 11.0 154 25 335 9.8 155 25 345 11.9 160 15 35 30.1 161 15 45 27.6 162 15 55 20.1 163 15 65 28.9 164 15 75 37.6 165 15 85 54.0 166 15 95 66.3 167 15 105 62.9 168 15 115 46.3 169 15 125 48.0 170 15 135 52.7 171 15 145 54.1 172 15 155 44.0 173 15 165 33.2 174 15 175 36.1 175 15 185 37.1 176 15 195 28.7 177 15 205 26.1 178 15 215 25.7 179 15 225 31.7 180 15 235 34.0 181 15 245 41.3 182 15 255 50.4 183 15 265 56.5 184 15 275 58.1 185 15 285 47.9 186 15 295 31.4 187 15 305 21.0 188 15 315 21.8 189 15 325 19.7 190 15 335 22.3 191 15 345 29.4 193 5 5 41.2 197 5 45 24.5 198 5 55 26.6 199 5 65 35.8 200 5 75 48.3 201 5 85 55.9 202 5 95 67.1 203 5 105 54.9 204 5 115 53.3 205 5 125 52.4 206 5 135 57.6 207 5 145 51.0 208 5 155 44.4 209 5 165 38.3 210 5 175 51.9 211 5 185 48.8 212 5 195 38.8 213 5 205 29.6 214 5 215 29.2 215 5 225 25.2 216 5 235 38.2 217 5 245 36.1 218 5 255 40.2 219 5 265 47.3 220 5 275 60.9 221 5 285 63.3 223 5 305 29.5 224 5 315 24.8 225 5 325 15.4 226 5 335 23.7 227 5 345 28.3 228 5 355 21.1 229 -5 5 22.5 230 -5 15 11.3 233 -5 45 18.4 234 -5 55 34.6 235 -5 65 41.0 236 -5 75 41.9 237 -5 85 52.0 238 -5 95 54.7 239 -5 105 41.8 240 -5 115 29.6 241 -5 125 27.2 242 -5 135 28.7 243 -5 145 41.6 244 -5 155 38.4 245 -5 165 47.6 246 -5 175 38.8 247 -5 185 39.7 248 -5 195 26.2 249 -5 205 31.4 250 -5 215 21.0 251 -5 225 9.5 252 -5 235 5.5 253 -5 245 7.0 254 -5 255 15.9 255 -5 265 22.6 256 -5 275 26.9 260 -5 315 16.2 261 -5 325 12.6 262 -5 335 10.0 263 -5 345 6.5 264 -5 355 11.3 265 -15 5 16.4 266 -15 15 22.1 268 -15 35 2.6 269 -15 45 7.1 270 -15 55 14.0 271 -15 65 11.7 272 -15 75 25.1 273 -15 85 20.5 274 -15 95 32.4 275 -15 105 17.7 276 -15 115 9.5 277 -15 125 8.9 278 -15 135 15.4 279 -15 145 16.7 280 -15 155 16.7 281 -15 165 22.3 282 -15 175 17.9 283 -15 185 33.1 284 -15 195 20.8 285 -15 205 17.5 286 -15 215 14.5 287 -15 225 11.3 288 -15 235 10.5 289 -15 245 8.1 290 -15 255 11.1 292 -15 275 26.9 293 -15 285 23.1 297 -15 325 18.3 298 -15 335 18.2 299 -15 345 12.6 300 -15 355 17.9 301 -25 5 15.8 302 -25 15 10.7 304 -25 35 7.3 305 -25 45 10.1 306 -25 55 9.1 307 -25 65 11.1 308 -25 75 16.2 309 -25 85 16.0 310 -25 95 12.2 311 -25 105 10.3 312 -25 115 8.2 316 -25 155 8.4 317 -25 165 13.9 318 -25 175 15.6 319 -25 185 21.7 320 -25 195 17.2 321 -25 205 27.4 322 -25 215 17.1 323 -25 225 24.7 324 -25 235 24.1 328 -25 275 16.7 329 -25 285 15.9 332 -25 315 26.3 333 -25 325 23.4 334 -25 335 18.2 335 -25 345 22.9 336 -25 355 21.7 337 -35 5 28.0 338 -35 15 16.2 339 -35 25 19.0 340 -35 35 13.7 341 -35 45 15.7 342 -35 55 19.9 343 -35 65 21.4 344 -35 75 14.5 345 -35 85 13.4 346 -35 95 19.1 347 -35 105 13.6 348 -35 115 13.5 349 -35 125 18.1 350 -35 135 21.9 351 -35 145 28.0 352 -35 155 17.9 353 -35 165 16.7 354 -35 175 13.8 355 -35 185 19.3 356 -35 195 15.5 357 -35 205 16.0 358 -35 215 16.3 364 -35 275 12.9 365 -35 285 22.0 367 -35 305 28.5 368 -35 315 26.6 369 -35 325 33.2 371 -35 345 28.6 372 -35 355 27.0 387 -45 145 22.3 388 -45 155 20.1 389 -45 165 18.3 390 -45 175 20.8 391 -45 185 19.9 400 -45 275 15.3 402 -45 295 36.4 403 -45 305 24.9 423 -55 290 32.2 424 -55 310 11.1 425 -55 330 17.4