Global cloud cover map showing an average of all of the cloud observations by NASA's Aqua satellite between July 2002 and April 2015. Colors range from dark blue (no clouds) to white (frequent clouds)

More info from the NASA page - There are three primary regions where clouds form:

A narrow strip near the equator, caused by the large scale circulation patterns—or Hadley cells—present in the tropics. Hadley cells are defined by cool air sinking near the 30 degree latitude line north and south of the equator and warm air rising near the equator where winds from separate Hadley cells converge. As warm, moist air converges at lower altitudes near the equator, it rises and cools and therefore can hold less moisture. This causes water vapor to condense into cloud particles and produces a dependable band of thunderstorms in an area known as the Inter Tropical Convergence Zone (ITCZ).

Clouds also tend to form in abundance in the middle latitudes 60 degrees north and south of the equator. This is where the edges of polar and mid-latitude (or Ferrel) circulation cells collide and push air upward, fueling the formation of the large-scale frontal systems that dominate weather patterns in the mid-latitudes. While clouds tend to form where air rises as part of atmospheric circulation patterns, descending air inhibits cloud formation. Since air descends between about 15 and 30 degrees north and south of the equator, clouds are rare and deserts are common at this latitude.

Clouds also tend to form off the west coasts of continents. This pattern is particularly clear off of South America, Africa, and North America. It occurs because the surface water of oceans gets pushed west away from the western edge of continents because of the direction Earth spins on its axis. In a process called upwelling, cooler water from deep in the ocean rises to replace the surface water. Upwelling creates a layer of cool water at the surface, which chills the air immediately above the water. As this moist, marine air cools, water vapor condenses into water droplets, and low clouds form. These lumpy, sheet-like clouds are called marine stratocumulus, the most common cloud type in the world by area. Stratocumulus clouds typically cover about one fifth of Earth’s surface.

/r/interestingasfuck Thread Link - eoimages.gsfc.nasa.gov