Despite a slight respite from three days of heavy fog, over 70 trains got delayed due to poor visibility in Delhi, which experienced a chilly on Tuesday.Several flights were also delayed or cancelled but airport officials refused to blame the fog for it.A light blanket of fog enveloped the city on Tuesday and the visibility at 8.30 am was 600 metres — better compared to Monday.Chilly winds continued to make Delhiites shiver as the minimum temperature settled three notches below average at 4.8°C.According to the Delhi International Airport Limited (DIAL) website, five flights were cancelled at the Indira Gandhi International (IGI) airport here due to low visibility at other airports where the flights were headed and technical reasons.Six domestic flights arriving in the national capital were delayed and five were cancelled.One international flight each was cancelled and delayed, according to a DIAL website post at 11.00 am.“Some flights were delayed due to bad weather conditions at other airports such as Patna. But things are far better today (Tuesday) than Monday,” an official in the operations arm of Air India said.However, DIAL in a statement said that no flights were cancelled due to foggy situation at IGI airport.On Monday, heavy fog conditions prevented 11 flights from taking off to various destinations in north India.“Eleven flights were cancelled yesterday (Monday) due to low visibility at other airports where the flights were to take off,” said IP Rao, chief executive of DIAL.Sounding the fog warning, the India Meteorological Department (IMD) on Tuesday said the condition is expected to last from Dec. 20 to Feb. 20.“The fog season has started from today and it will last upto Feb 20,” RK Jenamani, director, meteorological department (IGI airport) said.According to Jenamani, heavy fog will last for around 120 hours in the next two months and will affect runway visibility.According to a railway official, over 70 trains were delayed due to fog and 40 trains were cancelled.