Heavy fog enveloped several northern and eastern Chinese regions Sunday, with expressways being closed and over 110 flights delayed or canceled in Beijing.The foggy weather hit the cities of Beijing and Tianjin, and provinces of Hebei, Henan, Shandong, Anhui and Jiangsu Sunday morning, according to the National Meteorological Center.The Beijing Meteorological Center issued the first yellow alarm on heavy fog this autumn at 7:15 a.m. and forecast the fog would last another six hours.The visibility in Beijing was once reduced to as low as 200 meters in the early morning hours.Twenty-five flights at the Beijing Capital International Airport had been canceled and 88 more delayed by 10:45 a.m., according to the airport\'s operator.Meanwhile, the fog has forced the temporary closure of six expressways in Beijing, but the traffic in the downtown areas was not much affected on the non-working day, according to local police authorities.