At 10:05 a.m. local time (15:35 Universal Time) on February 14, 2016, the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite acquired this natural-color image of cloud streets spanning much of the East Coast of the United States. The day was marked by a high-pressure system that brought frigid temperatures and strong north and northwest winds to much of the region.
Cloud streets—long parallel bands of cumulus clouds—form when cold air blows over warmer water and a warmer air layer (temperature inversion) rests over the top of both. The water gives up heat and moisture to the cold air above, and columns of heated air naturally rise through the atmosphere. The temperature inversion acts like a lid, so when the rising thermals hit it, they roll over and loop back on themselves, creating parallel cylinders of rotating air. As this happens, the moisture cools and condenses into cumulus clouds that line up parallel to the direction of the prevailing winds.