URUMQI - Freezing fog left more than 5,000 passengers stranded at an airport in Northwest China's Xinjiang Uygur autonomous region on Friday.

Freezing fog is composed of droplets of supercooled water which freeze to surfaces on contact.

As of noon Friday, 77 outbound flights from the Diwopu International Airport in Urumqi were delayed and nine inbound ones were diverted to other cities in Xinjiang and Gansu province, according to the airport.

The visibility at the airport failed to meet the required level to allow take-off, it said.

Since Thursday, Urumqi has experienced rainfalls and a dramatic temperature drop. Airport authorities have activated an emergency response to handle the disruption.