File:Cloud streets in the Yellow Sea and the Sea of Japan (MODIS 2017-01-25).jpg

English: Frigid weather and strong, steady winds set the stage for a beautiful show of clouds off the shores of China, South Korea, North Korea, and Russia in late January 2017. The Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Terra satellite acquired this true-color image on January 22. Cloud streets are long parallel bands of cumulus clouds, which generally align with the prevailing wind. They form when cold air blows over warmer waters, and a warmer air layer (a temperature inversion) rests over the top of both. The comparatively warm water gives up heat and moisture to the cold air above, and columns of heated air called thermals naturally rise through the atmosphere. The temperature inversion acts like a lid. 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 flat-bottomed, fluffy-topped cumulus clouds that line up parallel to the direction if the prevailing winds.