On October 27, 2004, a thick curtain of aerosols hung over parts of northwestern India and Pakistan. A tight cluster of agricultural fires (marked in red) was burning and contributing smoke, which may have mixed with dust from nearby arid terrain and urban pollution from regional cities.
Air pollution is a serious environmental problem for the region. In 1999, an international team of scientists conducted an intensive field campaign to study the air pollution and its possible impacts on regional and global climate. Called the Indian Ocean Experiment (INDOEX), the effort provided worrisome evidence that the aerosol (particle) pollution existed in a layer as thick as 3 kilometers and spread thousands of kilometers away from the source. It persisted for weeks at a time throughout the winter. In addition to the impact on public health, the "brown cloud" may be diminishing the monsoon-related rainfall in southern Asia and reducing crop yields through the filtering of sunlight.
This image was captured by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite on October 27, 2004.NASA image created by Jesse Allen, Earth Observatory, using data obtained from the MODIS Rapid Response team.
