Ganges Delta Under a Winter Shroud of Fog
Winter weather settled across the Indo-Gangetic Plain in early January 2026, bringing dense fog and cold temperatures to much of the flat, fertile land stretching from Pakistan and northern India to Bangladesh.
This image shows low clouds over the delta on the morning of January 6, captured by the MODIS (Moderate Resolution Imaging Spectroradiometer) on NASA’s Terra satellite. Dense fog, especially radiative fog, is common at this time of year, forming when ground temperatures are cool, winds light, and moisture abundant near the surface. The Bangladesh and Indian Meteorological Services announced moderate to very dense fog over the region that day, amid an ongoing cold wave.
Other relatively low clouds extend from land and over the Bay of Bengal. These long, parallel bands of clouds, called cloud streets, can form when cold air passes over warmer open waters, gaining heat and moisture. Rising thermals rise until they reach a temperature inversion that acts like a lid, forcing air to roll into long, parallel rotating cylinders. Clouds form where air rises, while clear skies appear where air sinks.
Although it looks picturesque from above, foggy conditions can present dangers and disrupt daily life for people on the ground. For example, thick fog earlier this month caused significant disruptions at Dhaka International Airport, according to local media. Similar disruptions, as well as travel delays on roads and railways, were reported in parts of northern, central and eastern India.
NASA Earth Observatory image by Lauren Dauphin, using NASA MODIS data EOSDIS LANCE and GIBS/Worldview. Story by Kathryn Hansen.
References and resources
- Bangladesh Meteorological Department (January 5, 2026) Weather forecast valid for 120 hours from 6 p.m. of 05.01.2026. Accessed January 8, 2026.
- Dhaka Tribune (January 2, 2026) Flights are diverted one after another as thick fog disrupts operations at Dhaka airport. Accessed January 8, 2026.
- Indian Meteorological Department (January 5, 2026) Press release. Accessed January 8, 2026.
- NASA Earth Observatory (January 18, 2024) Fog covers the Indo-Gangetic plain. Accessed January 8, 2026.
- The new Indian Express (January 4, 2026) Cold wave persists in Delhi, northern India, with flights halted amid thick fog. Accessed January 8, 2026.
Downloads
January 6, 2025
You might also be interested in:
Stay up to date with the latest content from NASA as we explore the universe and discover more about our home planet.
4 minutes of reading
The right combination of conditions allowed these distinctive low clouds to form in California’s Central Valley for weeks.
5 minutes of reading
Scientists say seasonal crop fires are burning later in the day than in previous years.
3 minutes of reading
A prolonged high pressure system brought unusually warm temperatures in September to British Columbia and the Pacific Northwest.
Learn more about NASA Earth Science
