Publié le 2 juin 2020
Spend time on China’s Hainan Island, and chances are good that you will witness a lightning storm. Hainan and neighboring Guangdong province have the highest density of cloud-to-ground flashes and the most lightning related casualties in the country.
The clouds that frequently produce such severe weather—cumulonimbus—are seen building up during the afternoon. The image (top) was acquired at 2 p.m. China Standard Time (06:00 Universal Time) on May 11, 2020, with the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite. The time-series animation shows the growth of the clouds over the course of the day, as observed by Japan’s Himawari-8 satellite.
“It’s definitely a cumulonimbus cloud,” said Paul Markowski, a professor of meteorology at Pennsylvania State University. “And it’s sitting over the highest terrain in the center of the island.”
The south-central part of the island is mountainous, with elevations of more than 1800 meters (5,900 feet) surrounded by plains extending to the island’s northeast. The rugged topography creates orographic lift: when air moves across the plains and encounters the mountains, it is forced upward. So, when moist ocean air moves from low to high elevations, it cools and condenses into clouds.