Like Janus, the Greek god, the Indian monsoon has two faces, according to a report by researchers from Germany in the journal "Science".

The report says the monsoon convection not only transports pollutants upward all the way to the stratosphere (that starts at 18 km), from where they disperse globally, but it simultaneously provides a "cleansing mechanism" by removing particulate pollutants by precipitation with a key role played by lightning.