As the cold subsides, the Samhansami phenomenon, in which fine dust concentrations rise, continues to appear this winter.

As the cold Siberian high pressure weakens, the analysis shows that the wind is slowing and fine dust is flowing from China in a warm west wind.

According to the Air Pollution Homepage 'Air Korea' operated by the Korea Environment Corporation under the Ministry of Environment on the 9th, the average daily concentration of ultra-fine dust (PM-2.5) in Seoul was 45㎍ / ㎥ as of 10:00 am, and 'bad' (36 ～ 75㎍ / ㎥) level.

In addition to Seoul, Busan (36㎍ / ㎥), Daegu (39㎍ / ㎥), Gyeonggi (49㎍ / ㎥), Gangwon (36㎍ / ㎥), Chungbuk (48㎍ / ㎥), Chungnam (38㎍ / ㎥) Fine dust is 'bad' in most parts of the country, including Sejong (44㎍ / ㎥).

Last week, when the cold wave rose, it was a clear sky, and when the cold was released and the temperature was about the same or higher than normal, the concentration of fine dust increased.

In poetry, this phenomenon is called Samhansami.

According to the forces of Siberian high pressure, three days of cold and four days of fine dust are on the rise, while the three days of winter are cold and four days are relatively warm.

Scientifically, this expression is not without reason.

In Korea, the rise of fine dust concentration in winter is largely caused by two factors, both of which are closely related to temperature.

The first is that when cold Siberian high pressure in the cold north weakens, domestic temperatures are high, and high pressure stays in our country for a long time. At this time, the wind is calming and the air is congested.

The second time is when relatively mild southwest and west winds blow.

In this case, fine dust concentration may increase due to foreign factors such as China.

The rise in fine dust concentration on this day is an analysis that both factors are mixed.

As the cold wave receded last week, the air quality became turbid due to the inflow of foreign dust from the southwest and west winds as the temperature rose, the wind began to fade, and the concentration of domestic fine dust increased.

Clear skies are unlikely to be visible until 11 days.

In particular, on the 10th, the concentration of fine dust in Incheon and northern Gyeonggi is expected to rise to a very bad level.

It is expected that a high concentration of fine dust from China will follow from the southwest and west wind currents from the dawn of the 10th, with warm temperatures and fine dust accumulated.

An official from the National Institute of Environmental Sciences said, “At the late 11th afternoon, strong and fast northwest winds will push in, and the fine dust that has accumulated until the day after tomorrow will be resolved, and the fine dust will be resolved to some extent from 12th.”

When the sky is clear, the temperature is likely to drop slightly.

In fact, on the 12th, the expected minimum temperature is -3 degrees in Seoul, and the maximum temperature is expected to fall from 4 degrees to 10 days (minimum 4 degrees, maximum 11 degrees) and 11 days (minimum 7 degrees, maximum 9 degrees).

However, it will not deviate significantly from the average temperature.

(Photo = Yonhap News)