Cloud Fraction

Global Map Cloud Fraction Image 1 Global Map Cloud Fraction Image 2 Global Map Cloud Fraction Image 3 Global Map Cloud Fraction Image 4 Global Map Cloud Fraction Image 5 Global Map Cloud Fraction Image 6 Global Map Cloud Fraction Image 7 Global Map Cloud Fraction Image 8 Global Map Cloud Fraction Image 9 Global Map Cloud Fraction Image 10 Global Map Cloud Fraction Image 11 Global Map Cloud Fraction Image 12 Global Map Cloud Fraction Image 13 Global Map Cloud Fraction Image 14 Global Map Cloud Fraction Image 15 Global Map Cloud Fraction Image 16 Global Map Cloud Fraction Image 17 Global Map Cloud Fraction Image 18 Global Map Cloud Fraction Image 19 Global Map Cloud Fraction Image 20 Global Map Cloud Fraction Image 21 Global Map Cloud Fraction Image 22 Global Map Cloud Fraction Image 23 Global Map Cloud Fraction Image 24 Global Map Cloud Fraction Image 25 Global Map Cloud Fraction Image 26 Global Map Cloud Fraction Image 27 Global Map Cloud Fraction Image 28 Global Map Cloud Fraction Image 29 Global Map Cloud Fraction Image 30 Global Map Cloud Fraction Image 31 Global Map Cloud Fraction Image 32 Global Map Cloud Fraction Image 33 Global Map Cloud Fraction Image 34 Global Map Cloud Fraction Image 35 Global Map Cloud Fraction Image 36 Global Map Cloud Fraction Image 37 Global Map Cloud Fraction Image 38 Global Map Cloud Fraction Image 39 Global Map Cloud Fraction Image 40 Global Map Cloud Fraction Image 41 Global Map Cloud Fraction Image 42 Global Map Cloud Fraction Image 43 Global Map Cloud Fraction Image 44 Global Map Cloud Fraction Image 45 Global Map Cloud Fraction Image 46 Global Map Cloud Fraction Image 47 Global Map Cloud Fraction Image 48 Global Map Cloud Fraction Image 49 Global Map Cloud Fraction Image 50 Global Map Cloud Fraction Image 51 Global Map Cloud Fraction Image 52 Global Map Cloud Fraction Image 53 Global Map Cloud Fraction Image 54 Global Map Cloud Fraction Image 55 Global Map Cloud Fraction Image 56 Global Map Cloud Fraction Image 57 Global Map Cloud Fraction Image 58 Global Map Cloud Fraction Image 59 Global Map Cloud Fraction Image 60 Global Map Cloud Fraction Image 61 Global Map Cloud Fraction Image 62 Global Map Cloud Fraction Image 63 Global Map Cloud Fraction Image 64 Global Map Cloud Fraction Image 65 Global Map Cloud Fraction Image 66 Global Map Cloud Fraction Image 67 Global Map Cloud Fraction Image 68 Global Map Cloud Fraction Image 69 Global Map Cloud Fraction Image 70 Global Map Cloud Fraction Image 71 Global Map Cloud Fraction Image 72 Global Map Cloud Fraction Image 73 Global Map Cloud Fraction Image 74 Global Map Cloud Fraction Image 75 Global Map Cloud Fraction Image 76 Global Map Cloud Fraction Image 77 Global Map Cloud Fraction Image 78 Global Map Cloud Fraction Image 79 Global Map Cloud Fraction Image 80 Global Map Cloud Fraction Image 81 Global Map Cloud Fraction Image 82 Global Map Cloud Fraction Image 83 Global Map Cloud Fraction Image 84 Global Map Cloud Fraction Image 85 Global Map Cloud Fraction Image 86 Global Map Cloud Fraction Image 87 Global Map Cloud Fraction Image 88 Global Map Cloud Fraction Image 89 Global Map Cloud Fraction Image 90 Global Map Cloud Fraction Image 91 Global Map Cloud Fraction Image 92 Global Map Cloud Fraction Image 93 Global Map Cloud Fraction Image 94 Global Map Cloud Fraction Image 95 Global Map Cloud Fraction Image 96 Global Map Cloud Fraction Image 97 Global Map Cloud Fraction Image 98 Global Map Cloud Fraction Image 99 Global Map Cloud Fraction Image 100 Global Map Cloud Fraction Image 101 Global Map Cloud Fraction Image 102 Global Map Cloud Fraction Image 103 Global Map Cloud Fraction Image 104 Global Map Cloud Fraction Image 105 Global Map Cloud Fraction Image 106 Global Map Cloud Fraction Image 107 Global Map Cloud Fraction Image 108 Global Map Cloud Fraction Image 109 Global Map Cloud Fraction Image 110 Global Map Cloud Fraction Image 111 Global Map Cloud Fraction Image 112 Global Map Cloud Fraction Image 113 Global Map Cloud Fraction Image 114 Global Map Cloud Fraction Image 115 Global Map Cloud Fraction Image 116 Global Map Cloud Fraction Image 117 Global Map Cloud Fraction Image 118 Global Map Cloud Fraction Image 119 Global Map Cloud Fraction Image 120 Global Map Cloud Fraction Image 121 Global Map Cloud Fraction Image 122 Global Map Cloud Fraction Image 123 Global Map Cloud Fraction Image 124 Global Map Cloud Fraction Image 125 Global Map Cloud Fraction Image 126 Global Map Cloud Fraction Image 127 Global Map Cloud Fraction Image 128 Global Map Cloud Fraction Image 129 Global Map Cloud Fraction Image 130 Global Map Cloud Fraction Image 131 Global Map Cloud Fraction Image 132 Global Map Cloud Fraction Image 133 Global Map Cloud Fraction Image 134 Global Map Cloud Fraction Image 135 Global Map Cloud Fraction Image 136 Global Map Cloud Fraction Image 137 Global Map Cloud Fraction Image 138 Global Map Cloud Fraction Image 139 Global Map Cloud Fraction Image 140 Global Map Cloud Fraction Image 141 Global Map Cloud Fraction Image 142 Global Map Cloud Fraction Image 143 Global Map Cloud Fraction Image 144 Global Map Cloud Fraction Image 145 Global Map Cloud Fraction Image 146 Global Map Cloud Fraction Image 147 Global Map Cloud Fraction Image 148 Global Map Cloud Fraction Image 149 Global Map Cloud Fraction Image 150 Global Map Cloud Fraction Image 151 Global Map Cloud Fraction Image 152 Global Map Cloud Fraction Image 153 Global Map Cloud Fraction Image 154 Global Map Cloud Fraction Image 155 Global Map Cloud Fraction Image 156 Global Map Cloud Fraction Image 157 Global Map Cloud Fraction Image 158 Global Map Cloud Fraction Image 159 Global Map Cloud Fraction Image 160 Global Map Cloud Fraction Image 161 Global Map Cloud Fraction Image 162 Global Map Cloud Fraction Image 163 Global Map Cloud Fraction Image 164 Global Map Cloud Fraction Image 165 Global Map Cloud Fraction Image 166 Global Map Cloud Fraction Image 167 Global Map Cloud Fraction Image 168 Global Map Cloud Fraction Image 169 Global Map Cloud Fraction Image 170 Global Map Cloud Fraction Image 171 Global Map Cloud Fraction Image 172 Global Map Cloud Fraction Image 173 Global Map Cloud Fraction Image 174 Global Map Cloud Fraction Image 175 Global Map Cloud Fraction Image 176 Global Map Cloud Fraction Image 177 Global Map Cloud Fraction Image 178 Global Map Cloud Fraction Image 179 Global Map Cloud Fraction Image 180 Global Map Cloud Fraction Image 181 Global Map Cloud Fraction Image 182 Global Map Cloud Fraction Image 183 Global Map Cloud Fraction Image 184 Global Map Cloud Fraction Image 185 Global Map Cloud Fraction Image 186 Global Map Cloud Fraction Image 187 Global Map Cloud Fraction Image 188 Global Map Cloud Fraction Image 189 Global Map Cloud Fraction Image 190 Global Map Cloud Fraction Image 191 Global Map Cloud Fraction Image 192 Global Map Cloud Fraction Image 193 Global Map Cloud Fraction Image 194 Global Map Cloud Fraction Image 195 Global Map Cloud Fraction Image 196 Global Map Cloud Fraction Image 197 Global Map Cloud Fraction Image 198 Global Map Cloud Fraction Image 199 Global Map Cloud Fraction Image 200 Global Map Cloud Fraction Image 201 Global Map Cloud Fraction Image 202 Global Map Cloud Fraction Image 203 Global Map Cloud Fraction Image 204 Global Map Cloud Fraction Image 205 Global Map Cloud Fraction Image 206 Global Map Cloud Fraction Image 207 Global Map Cloud Fraction Image 208 Global Map Cloud Fraction Image 209 Global Map Cloud Fraction Image 210 Global Map Cloud Fraction Image 211 Global Map Cloud Fraction Image 212 Global Map Cloud Fraction Image 213 Global Map Cloud Fraction Image 214 Global Map Cloud Fraction Image 215 Global Map Cloud Fraction Image 216 Global Map Cloud Fraction Image 217 Global Map Cloud Fraction Image 218 Global Map Cloud Fraction Image 219 Global Map Cloud Fraction Image 220 Global Map Cloud Fraction Image 221 Global Map Cloud Fraction Image 222 Global Map Cloud Fraction Image 223 Global Map Cloud Fraction Image 224 Global Map Cloud Fraction Image 225 Global Map Cloud Fraction Image 226 Global Map Cloud Fraction Image 227 Global Map Cloud Fraction Image 228 Global Map Cloud Fraction Image 229 Global Map Cloud Fraction Image 230 Global Map Cloud Fraction Image 231 Global Map Cloud Fraction Image 232 Global Map Cloud Fraction Image 233 Global Map Cloud Fraction Image 234 Global Map Cloud Fraction Image 235 Global Map Cloud Fraction Image 236 Global Map Cloud Fraction Image 237 Global Map Cloud Fraction Image 238 Global Map Cloud Fraction Image 239 Global Map Cloud Fraction Image 240 Global Map Cloud Fraction Image 241 Global Map Cloud Fraction Image 242 Global Map Cloud Fraction Image 243 Global Map Cloud Fraction Image 244 Global Map Cloud Fraction Image 245 Global Map Cloud Fraction Image 246 Global Map Cloud Fraction Image 247 Global Map Cloud Fraction Image 248 Global Map Cloud Fraction Image 249 Global Map Cloud Fraction Image 250 Global Map Cloud Fraction Image 251 Global Map Cloud Fraction Image 252 Global Map Cloud Fraction Image 253 Global Map Cloud Fraction Image 254 Global Map Cloud Fraction Image 255 Global Map Cloud Fraction Image 256 Global Map Cloud Fraction Image 257 Global Map Cloud Fraction Image 258 Global Map Cloud Fraction Image 259 Global Map Cloud Fraction Image 260 Global Map Cloud Fraction Image 261 Global Map Cloud Fraction Image 262 Global Map Cloud Fraction Image 263 Global Map Cloud Fraction Image 264 Global Map Cloud Fraction Image 265 Global Map Cloud Fraction Image 266 Global Map Cloud Fraction Image 267 Global Map Cloud Fraction Image 268 Global Map Cloud Fraction Image 269 Global Map Cloud Fraction Image 270 Global Map Cloud Fraction Image 271 Global Map Cloud Fraction Image 272 Global Map Cloud Fraction Image 273 Global Map Cloud Fraction Image 274 Global Map Cloud Fraction Image 275 Global Map Cloud Fraction Image 276 Global Map Cloud Fraction Image 277 Global Map Cloud Fraction Image 278 Global Map Cloud Fraction Image 279 Global Map Cloud Fraction Image 280 Global Map Cloud Fraction Image 281 Global Map Cloud Fraction Image 282 Global Map Cloud Fraction Image 283 Global Map Cloud Fraction Image 284 Global Map Cloud Fraction Image 285 Global Map Cloud Fraction Image 286 Global Map Cloud Fraction Image 287 Global Map Cloud Fraction Image 288 Global Map Cloud Fraction Image 289 Global Map Cloud Fraction Image 290 Global Map Cloud Fraction Image 291 Global Map Cloud Fraction Image 292 Global Map Cloud Fraction Image 293 Global Map Cloud Fraction Image 294 Global Map Cloud Fraction Image 295 Global Map Cloud Fraction Image 296
Cloud Fraction
Cloud Fraction Scale

In addition to their role as rain- and snow-makers in Earth's water cycle, clouds play a major part in Earth's energy budget—the balance of energy that enters and leaves the climate system. Clouds may have a warming or cooling influence depending on their altitude, type, and when they form. Clouds reflect sunlight back into space, which causes cooling. But they can also absorb heat that radiates from the Earth's surface, preventing it from freely escaping to space. One of the biggest sources of uncertainty in computer models that predict future climate is how clouds influence the climate system and how their role might change as the climate warms.

These maps show what fraction of an area was cloudy on average each month. The measurements were collected by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite. Colors range from blue (no clouds) to white (totally cloudy). Like a digital camera, MODIS collects information in gridded boxes, or pixels. Cloud fraction is the portion of each pixel that is covered by clouds. Colors range from blue (no clouds) to white (totally cloudy).

From month to month, a band of clouds girdles the equator. This band of persistent clouds is called the Intertropical Convergence Zone, the place where the easterly trade winds in the Northern and Southern Hemispheres meet. The meeting of the winds pushes warm, moist air high into the atmosphere. The air expands and cools, and the water vapor condenses into clouds and rain. The cloud band shifts slightly north and south of the equator with the seasons. In tropical countries, this shifting of the Intertropical Convergence Zone is what causes rainy and dry seasons.

Another frequently cloudy place is the Southern Ocean. Although there is not as much evaporation in the high latitudes as in the tropics, the air is cold. The colder the air, the more readily any water vapor in the air will condense into clouds.

View, download, or analyze more of these data from NASA Earth Observations (NEO):
Cloud Fraction