A combination of clouds and heavy haze hung over China’s Sichuan Basin in late February 2009. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite took this picture of the region on February 24, 2009.
Clouds obscure the satellite’s view of Sichuan’s capital city, Chengdu, in this image. West of the city, skies are clear, revealing snow-capped peaks. South and east of the city, however, thick haze fills the lowlands, snaking into valleys along the basin’s perimeter. The haze likely results from urban and industrial pollution, and perhaps from residential heating with coal or wood-burning stoves. Haze in this region tends to worsen in the winter, when cold, heavy air traps pollutants near the surface.