File:Fire and Smoke in India (MODIS 2021-02-28).jpg

English: Winter haze continued to blanket northern India in late February 2021. A regular visitor in winter, haze piles up along the southern front of the Himalaya Mountains and pours across the Indian Ocean. On February 24, 2021, when the Moderate Resolution Imaging Spectroradiometer (MODIS) on board NASA’s Terra satellite acquired a true-color image of the region, the haze was so thick that it obscured the ground from view. Wintertime temperature inversions contribute to the build up of haze. Inversions occur when cold air gets trapped under a layer of warm air. Usually, air high in the atmosphere is cooler than air near Earth’s surface. Warmer air near the surface rises, allowing pollutants from the surface to disperse in the atmosphere. During the winter, cold air often moves down the Himalaya Mountains, settling over northern India’s Ganges Plain. This layer of cold air gets trapped beneath a layer of warmer air. Since the cold air cannot rise above the warm air, pollution builds in the cold air as long as the temperature inversion lasts.