What are the weather characteristics of smog?

Fog is a common disastrous weather phenomenon, and its occurrence is closely related not only to the weather system, but also to the underlying surface and topography. The formation of fog is very local, which is determined by rich water vapor content in the atmosphere, relatively stable stratification in the air near the ground, warm air flowing through the cold surface area or severe radiation cooling. According to the causes of fog formation, fog can be roughly divided into two categories: one is frontal fog, high-pressure fog and low-pressure fog under the influence of weather system; The other is advection fog, radiation fog and evaporation fog formed by the nature of the underlying surface. In addition, there is uphill fog affected by the terrain. Generally speaking, coastal areas, mountainous areas and cities are foggy areas. The inland areas of China are mostly radiation fog, and the coastal areas are mostly advection fog. Mountain fog can often be seen on windward slopes in mountainous areas, and frontal fog can often be seen in areas and seasons with frequent frontal activities. There is fog all year round in our country, which is foggy in most areas in autumn and winter, and less in spring and summer.

Occurrence characteristics of haze

Smog in most parts of the country has obvious seasonal changes, and its basic characteristics are: more in winter, less in summer, and middle in spring and autumn. The weather conditions when haze occurs are characterized by stable and dry air masses. There are many days in winter to meet such weather conditions, and some places use coal for heating, which is dusty and easy to form smog. In most parts of China, it is rainy in summer, local convection is strong, and rainfall is abundant compared with other seasons, which washes away pollutants such as dust in the air and is not conducive to the formation of haze weather.