When will the persistent smog dissipate?

After continuous rainfall, the smog is easy to dissipate. Rainwater can remove particles, and the main mechanism is inertial collision and interception. Without particles, the smog naturally dissipates.

Imagine that particles of different sizes are suspended in the air and a drop of rain falls from the air. Large particles in the path of raindrops can't "dodge" before they are removed when they touch raindrops. This is an inertial collision. Although some particles "dodge" with the airflow, they are a combination of fog and haze because of the existence of smog. Smog is very common in cities. In many areas of China, fog and haze are combined as disastrous weather phenomena for early warning and forecasting, which are collectively called "haze weather".

Haze is the result of interaction between specific climatic conditions and human activities. The economic and social activities of high-density population will inevitably emit a large number of fine particles (PM 2.5). Once the emission exceeds the atmospheric circulation capacity and carrying capacity, the concentration of fine particles will continue to accumulate. At this time, if it is affected by calm weather, it is easy to have a wide range of smog.

In 20 13, "smog" became the key word of the year. In June 5438+10, four smog processes enveloped 30 provinces (autonomous regions and municipalities). In Beijing, only five days are not foggy. It is reported that less than 65,438+0% of the 500 largest cities in China meet the air quality standards recommended by the World Health Organization. Meanwhile, among the 65,438+00 most polluted cities in the world, 7 are in China.