Thick fog has spread across the Indo-Gangetic Plain this week, stretching from Pakistan, across India, into Bangladesh.

As a result of the fog, flights and trains have seen delays and cancellations in some places due to lack of visibility.

The fog was captured from above by NASA satellite Terra, and was also visible on the WeatherRadar on January 15 as the satellite image was captured.

Much of the fog is a form known as radiation fog which develops overnight as ground temperatures fall and moisture in the air grows.

Combine these with slower winds and the dense form of fog is created.

Learn more about how different forms of fog develop with our Weather Explained video:

Research from the University of East Anglia and the University of Leeds suggests that fog across the Indo-Gangetic Plain is becoming more frequent and more intense.

The study looked at fog outbreaks from 2000 to 2020 and suggests that rising aerosol pollution from urbanisation is a likely cause.

Alongside the fog, temperatures across parts of India are falling in a cold wave. This is spreading across the state of Madhya Pradesh with temperatures dropping 4 to 7°C below normal.