At least 40 flights have been affected due to thick fog which enveloped the Indian capital Monday morning, a senior aviation official said. "Some 40 flights to and from the Indira Gandhi International Airport in the national capital were delayed as both runways had to be shut down due to dense fog. A couple of flights were also diverted to the northern state of Rajasthan's capital Jaipur. The situation has started improving," he said on condition of anonymity. Fog suddenly blanketed the Indian capital after some two weeks of clear sky and the weather department predicts sunny days ahead. Fog is common in northern India only during the winter months of December and January