Haze lingered along the southern face of the Himalaya in early December 2011, continuing a pattern that had lasted for weeks. The the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this natural-color image on December 5, 2011. Haze forms an arc over Nepal and northern India. Over Bangladesh, haze flows southward toward the Bay of Bengal.
At this time of year, cold air often slides down the Himalaya, coming to rest over northern India. As the cold air settles into place, it may be trapped under a layer of warmer air. Usually, air is warmer near the Earth’s surface, and cooler higher in the atmosphere. Cold air trapped under warm air, known as a temperature inversion, can contribute to the buildup of haze, because the cold air cannot rise above the warm air and disperse pollutants.