Spectacular cloud streets surrounded southern Greenland in late winter, 2012. The Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Aqua satellite captured this true-color image on March 6, 2012.
Cloud streets are bands of cumulus clouds that form parallel to the low-level wind direction when conditions are right. They form by convection, a process in which warm air rises and cold air sinks. When the sun shines, moist air at the ground level begins to rise. As it rises, it cools and when moist air cools to a critical temperature water condenses onto tiny particles suspended in the atmosphere and clouds are formed.
Cloud streets form in the planetary boundary layer, within the lower one to three kilometers of the atmosphere, and can form over water or land. Although beautiful when seen from below, when patterns stretch across hundreds of kilometers the view is best from above. Aqua, as well as Terra, from their orbits at 705 kilometers above sea level, offer especially stunning looks at cloud patterns.