Dense fog on Tuesday morning reduced visibility in most parts of Haryana and Punjab, affecting traffic movement. The fog reduced visibility in several parts of the two states including Haryana's Karnal, Ambala, Hisar, Rohtak, Bhiwani and Panchkula and Punjab's Amritsar, Ludhiana, Patiala, Halwara, Adampur, Bathinda, Mohali and Rupnagar, according to a meteorological department official.