Bitterly cold winter weather in eastern Asia set the stage for a spectacular cloud show over the Yellow Sea and Sea of Japan in early January, 2014. The Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Terra satellite captured this true-color image of the event on January 9.
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.
On January 9 snow covered northeastern China, southeastern Russia, and North Korea. South Korea was cold, but only spotted with snow. Winds blew from the northwest, bringing cold air over the Yellow Sea (south) and the Sea of Japan (north), and creating a long band of cloud streets. On that day, the high temperature in Vladivostok, Russia was 10°F (-12°C) and the low was -7°F (-21°C).