December 12, 2014 - Kashmir Valley, India

Kashmir Valley, India

About 4.5 million years ago, the Kashmir Valley was at the bottom of a large lake, encircled by a ring of rugged mountains. Much of the lake’s water has long since drained away through an outlet channel on the valley’s west side. However, evidence of the lake remains in the bowl-like shape and the clay and sand deposits on the valley floor.

The mountains surrounding Kashmir Valley now trap air a bit like they once trapped water. The high ridges can set up airflow patterns that concentrate smoke and other airborne pollutants near the valley floor, causing outbreaks of haze. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this true-color image of haze in the valley on December 5, 2014.

Haze is most likely to occur when warm, buoyant air moves over cooler, denser air—a situation meteorologists call an inversion. Temperature inversions often develop on winter nights as the surface loses heat and chills the air immediately above. Mountain valleys often strengthen inversions because cold air from mountaintops tends to flow down slopes and push warmer air up from the floor in the process. Snow cover also increases the likelihood of an inversion because snow cools the air near the surface by reflecting much of the Sun’s energy rather than absorbing it. With a temperature inversion in place, air in the valley becomes stagnant; the warm air above it acts like a cap and prevents pollutants from dispersing.

Much of the haze visible in the image likely had its origins in charcoal production or the burning of biomass. Charcoal is widely used to heat homes in the Kashmir Valley in the winter and emits several types of polluting gases and aerosol particles into the atmosphere.

Image Facts
Satellite: Terra
Date Acquired: 12/5/2014
Resolutions: 1km ( B), 500m ( B), 250m ( B)
Bands Used: 1,4,3
Image Credit: Jeff Schmaltz, MODIS Land Rapid Response Team, NASA GSFC