RK Jenamani, director-in-charge of IGI Met department, said the squall was caused by the strong interaction of two separate phenomenon. One was a huge column of a cumulonimbus (CB) cloud, as high as 14 km, which moved from the southwest through Central Delhi towards the Northeast.
The other phenomenon was massive dust clouds in West Delhi and around the airport.
The two phenomena were well separated and interacted strongly to cause this massive dust storm at the airport and a moist squall and rainfall in rest of the city, Jenamani said.
The storm affected parts of northeast Haryana and the NCR regions, with parts of East Delhi, Noida and Ghaziabad reported to be the worst affected. The immediate impact was a fall in the maximum temperature, which plunged from 45.8 degree Celsius on Thursday to 30.4 degrees today.
Director General of the Indian Meteorological Department, L S Rathore, said the squall on Friday was a result of cold air and hot air meeting over the Indo-Gangetic plains.
This phenomena is likely to continue for the next two days, he said.