Originally Posted by
SQ421
Fog in Delhi, from memory, tends to build up closer to sunrise and stick around till mid morning if things are that worse. Caused with a combination of warmer air (closer to sunrise) meeting the cold land.
I don't know about fog in DEL, but the other day I was trying to pull an all-nighter mugging for an important exam... Around 3 AMish, I decided to go for a run to get some blood flowing. To my shock, I could barely see 5 feet ahead of me... I didn't know that HYD deals with fog too.. Or maybe it was smog

By 6 AM, fog was gone.
Also, not sure how AI manages to get their flights out an 100 minutes late - that's around 4:30 AM, which I would think would be the peak fog period...