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December 6, 2025 - Aerosols over India and Bangladesh
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Widespread haze and smog blanketed northern India, Bangladesh, and the Bay of Bengal in early December 2025, turning skies gray and creating hazardous air quality near the ground.
The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite acquired this true-color image of the region on December 5. At that time, haze spread widely over almost all of the visible land south of the Himalayas, while air over the peaks of the mountains and the high Tibetan Plateau appeared crystal clear. The silvery sheen over the Bay of Bengal is likely the result of a combination of cloud, thick aerosol (tiny particles of pollution suspended in air), and sunglint. Sunglint is an optical phenomena caused when light from the Sun strikes the surface and is reflected directly back to the sensor on the instrument.
According to reporting by India Today, Delhi, India recorded an Air Quality Index (AQI) of 324 on the morning of December 5, placing it in the “very poor” category of air quality. Also, according the report, 30 of 39 monitoring stations gave readings in the “very poor” category with only 9 registering “poor” early that same morning. The website AQI.IN reported that AQI in Delhi reached 332 later that evening, placing the city’s air in the “Hazardous” category.
Wintertime haze is a common hazard in northern India and Bangladesh. The pollutants that contribute to the gray and sometimes hazardous air include smoke from agricultural fires, industrial pollution, coal and biomass burning for heat, automobiles, among other lesser contributors.
As temperatures cool in late autumn and winter, pollutants can be trapped near the land surface by temperature inversions. 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, which may be for days or weeks.
Image Facts
Satellite:
Terra
Date Acquired: 12/5/2025
Resolutions:
1km (971.8 KB), 500m (2 MB), 250m ( B)
Bands Used: 1,4,3
Image Credit:
MODIS Land Rapid Response Team, NASA GSFC
Widespread haze and smog blanketed northern India, Bangladesh, and the Bay of Bengal in early December 2025, turning skies gray and creating hazardous air quality near the ground.
The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite acquired this true-color image of the region on December 5. At that time, haze spread widely over almost all of the visible land south of the Himalayas, while air over the peaks of the mountains and the high Tibetan Plateau appeared crystal clear. The silvery sheen over the Bay of Bengal is likely the result of a combination of cloud, thick aerosol (tiny particles of pollution suspended in air), and sunglint. Sunglint is an optical phenomena caused when light from the Sun strikes the surface and is reflected directly back to the sensor on the instrument.
According to reporting by India Today, Delhi, India recorded an Air Quality Index (AQI) of 324 on the morning of December 5, placing it in the “very poor” category of air quality. Also, according the report, 30 of 39 monitoring stations gave readings in the “very poor” category with only 9 registering “poor” early that same morning. The website AQI.IN reported that AQI in Delhi reached 332 later that evening, placing the city’s air in the “Hazardous” category.
Wintertime haze is a common hazard in northern India and Bangladesh. The pollutants that contribute to the gray and sometimes hazardous air include smoke from agricultural fires, industrial pollution, coal and biomass burning for heat, automobiles, among other lesser contributors.
As temperatures cool in late autumn and winter, pollutants can be trapped near the land surface by temperature inversions. 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, which may be for days or weeks.
Image Facts
Satellite:
Terra
Date Acquired: 12/5/2025
Resolutions:
1km (971.8 KB), 500m (2 MB), 250m ( B)
Bands Used: 1,4,3
Image Credit:
MODIS Land Rapid Response Team, NASA GSFC
