Dense fog in the National Capital disrupted Air operations for the fourth day today. More than 50 domestic and international flights were badly affected. According to a spokesman of Delhi airport three morning flights were cancelled, while 32 domestic and 20 international ones were delayed by over three to four hours as thick fog blanketed the IGI airport.<br/><br/>The runway visibility dipped to a low of 75 metres at around 3.30 am and again around 7.30 am this morning. After the visibility become poor some flights landed with the help of CAT-III B instrument landing system (ILS). Our correspondent who visited the airport reports that a large number of people are stranded due to cancellation and delay in flights. We spoke to a passenger who is on the airport on the second day to leave for his destination.<br/><br/>According to Railways 68 trains have been cancelled and 42 others were rescheduled due to foggy conditions. Another 122 trains are running more than three hours behind the schedule. Our correspondent says confusion prevails at different railway stations in Delhi as passengers have to wait for days to board their trains. The road traffic in the national capital was also affected due to fog. The Railway Ministry had made it clear that the train drivers have been asked to move at a slower pace due to fog to avoid accidents and this is the main reason for delay and re-scheduling of trains. <br/><br/>With traffic restrictions on many routes due to Dress Rehearsal of the Republic Day Parade in Delhi, traffic jams could be seen at many places with buses and cars moving at a slow pace with their headlights on. Weatherman says foggy conditions are likely to continue for next couple of days. The maximum and minimum temperatures are expected to be around 21 degrees and nine degrees celsius.