More than three dozen flights were delayed and several trains were running late as a thick blanket of fog enveloped Delhi and nearby regions on Monday morning.br br Morning temperatures were down several notches, and visibilty was at a bare minimum severely, spelling trouble for schoolchildren and early office-goers.br br Reports said than more than 50 trains across the north, including the North-East Express and Mahabodhi Express were running late by several hours due to a thick blanket of fog.