Fog has a serious impact on water, land and air traffic and power transmission. The influence of fog on traffic is mainly caused by the decrease of visibility. Land traffic (especially highways) is often completely paralyzed by heavy fog, even causing casualties. For example, on the morning of 1977 12 17, a 40-car pileup accident occurred on the Beijing-Tianjin Expressway due to heavy fog, resulting in 9 deaths and 17 injuries. In navigation and river transportation, if fog interferes with the waterway or port, the ship can't sail and even cause serious collision accidents. Some offshore production departments regard sea fog as "tiger weather". According to the survey, nearly 80% of all vicious maritime accidents in Qingdao Maritime Safety Administration are caused by sea fog. For example, on June 1975 and 19, the dense fog affected the line of sight in JIAOZHOU Bay, resulting in four consecutive major average accidents on the same day. In the aviation industry, a heavy fog often makes planes change planes, delay flights and cancel flights. The harm of fog to transmission is that fog drops adhere to the surface of insulation equipment such as porcelain bottles and hanging bottles of transmission lines, which leads to the decline of insulation performance of transmission and transformation equipment and the short circuit trip of high voltage lines, which is called "pollution flashover disaster". For example, from 65438 to mid-February of 1990, heavy fog filled North China, especially Beijing, Tianjin and Tangshan. Heavy fog damaged the porcelain insulators of high-voltage transmission lines, causing frequent pollution flashover, power grid disconnection and large-scale power outage, resulting in economic losses of hundreds of millions of yuan. In addition, when there is wind, the rime formed by supercooled fog on transmission lines often causes disconnection accidents. Fog also brings inconvenience and difficulties to people's daily life. Due to excessive humidity, people's breathing is not smooth and their mood is low, which obviously increases the incidence of respiratory diseases and joint, waist and leg pain. Persistent fog will aggravate the air pollution in the city.
2. Regional distribution of fog
Fog is very local, so its distribution is not very regular with the region. Generally speaking, the general distribution trend of the whole country is that there are more in the southeast and less in the northwest, and the foggy days in some parts of the southeast exceed 10 ~ 15 days every year; However, most areas in the northwest only last for about 3 days, and some high mountain areas can exceed 10 ~ 25 days. Arid basins such as Tarim, Qaidam, Turpan and Junggar, and arid valley areas such as Batang, Derong, Jinchuan and Danba in western Sichuan are the places with the least foggy days in half of northwest China, with an annual average of less than 1 day. There are many foggy areas with foggy days exceeding 25 days in the whole year, such as Daxinganling, Changbai Mountain Range and Qian Shan Mountains in the northeast, Tianshan Mountains in Xinjiang and Qinling Mountains in Shaanxi in the northwest, Jiangsu and Zhejiang coastal areas in the south, mountainous areas in the northwest of Fujian, Sichuan Basin, mountainous areas at the junction of Hunan, Hubei and Guizhou, southwestern Yunnan and southeastern Tibet. The foggy areas with an average annual foggy day of more than 50 days are limited to the coastal areas of Liaoning in the north and scattered mountainous areas such as the mountainous areas in the northwest of Fujian, southwestern Yunnan and southeastern Tibet in the south. Northwest Fujian and southwest Yunnan are also extremely foggy areas with annual fog days exceeding 100 in China. Among them, the average annual foggy days in Mengla, Xishuangbanna are 149.3 days, Yun Jinghong 105.2 days, Lancang19.5 days, and Taining 144.5 days in northwest Fujian. Known as the "foggy city", Chongqing and Shapingba Meteorological Station have an average annual foggy days of 69.3 days, much less than Xishuangbanna and northwest Fujian. The place with the most foggy days in China is Emei Mountain Meteorological Station in Sichuan Province, with an altitude of 3,047 meters and an annual average foggy day of 31961~1990, which is the highest foggy day in China.
The ocean is rich in water vapor and generally foggy. For example, the average foggy day in Hongjia along the coast of Zhejiang Province is only 3 1.2 days, while it is as many as 134.2 days in Chenda Island not far from it. Chengshantou on the northern coast is known as the "fog cave", with an average annual fog day of 82. O days, while Jinan inland at the same latitude is only 18. 1 day. However, there is little fog in the tropical ocean, and Yulin Port at the southern end of Hainan Island is also known as the "fog-free port".