File:Cloud Streets over the Sea of Japan (MODIS 2021-12-24).jpg

English: Frigid temperatures and strong winds swept across eastern Russia on December 22, 2021, dropping air temperatures as low as -2˚F (-18.9˚C). As the cold air blew across the Sea of Japan, a spectacular array of clouds formed across the relatively warm waters. NASA’s Terra satellite passed over the region on that same day, allowing the Moderate Resolution Imaging Spectroradiometer (MODIS) to capture a stunning true-color image of the scene.

The long bands of cloud stretch from just off the shore of Russia’s Primorsky Krai to reach Honshu and Hokkaido, two of the largest islands of Japan—a distance exceeding 400 miles (644 km). These bands of cumulus clouds, which orient themselves almost parallel to the low-level wind direction are known as “cloud streets”.

Cloud streets typically form when cold air blows over warmer water. To transport the heat away from the sea surface, columns of heated air called thermals naturally rise through the atmosphere. The air masses rise until they hit a warmer air layer (temperature inversion), which acts like a lid. The rising thermals then roll over and loop back on themselves, creating parallel cylinders of rotating air. On the upper edge of these cylinders of air, clouds form. Along the downward side (descending air), skies are clear.