Relevance: GS-III (Environment, Air Pollution); Source: NASA Earth Science

News

NASA has reported that farmers in Punjab, Haryana and Uttar Pradesh are now burning paddy stubble later in the day (around 4–6 p.m.), rather than the earlier 1–2 p.m. window. This shift is affecting how India detects and manages farm fires.

Why the Timing Shift Matters

• Most monitoring satellites pass in the early afternoon, so late-day fires are missed or under-counted.
• This leads to incomplete estimates of stubble burning during peak pollution season.
• Evening burning also coincides with temperature inversion, which traps smoke close to the ground and worsens winter smog across the Indo-Gangetic Plain.

The Science Behind Satellite Detection 

• Satellites detect fires through thermal infrared sensors that pick up heat, and visible–infrared bands that detect smoke plumes.
  
• Polar-orbiting satellites (MODIS, VIIRS) pass only once or twice in early afternoon, so they miss evening fires.
  
• Geostationary satellites capture images throughout the day, helping detect late-day burning more accurately.

General Situation of Stubble Burning in India

Despite alternative technologies, stubble burning remains common due to high costs, time pressure, and limited access to machinery for residue management.

Q. Which of the following explains why many farm fires in northern India go undetected by satellites?

1. Most fires now occur in the late evening.
2. Polar-orbiting satellites pass mainly in the early afternoon.
3. Geostationary satellites cannot capture fire images.

A. 1 and 2 only
B. 2 and 3 only
C. 1 and 3 only
D. All three