| Fog disasters seriously influence aviation flood and field transportation. Beijing is our country's political economic center, the transportation is busy, the industry is numerous, there are many national significant politics cultural event, fog disasters create many national economy loss and bad social impact. Implementing successful artificial fog dissipation has prominent society, politics, economic significance. This main purpose of this article is to study the macroscopic physical feature of fog in Beijing reigon. and to do the laboratory experiment. on a new environmental protection agent called RC/XW in order to understand it's fog dissipation capability.,seeding the suitable methods to Beijing reigon.Using Beijing Observatory fog observed data from 1981 to 2006, this paper make the statistical analysis on the interannual variability, monthly variability of the fog in Beijing, on fog visibility, fog formation time as well as fog duration, the changes of fog occurrence frequency along with the temperature, the characteristics of temperature and humidity during the occurrence time of the fog while the relations between the occurrence of the fog in Beijing and wind direction,wind speed as well as the height of fog top. The conclusion are as followed .The fog interannual variability is extremely non-uniform, there are many fog in fall and winter, fewer fog in spring. The visibility of fog in Beijing is low so it influente the transportation seriously. Warm fog's occurrence rate is far higher than the cold fog. The majority of fog formed before the sunrise and before the midnight. Beijing cold fog average duration is longer than the warm fog. Around 0℃, occurrence frequency is the highest. When cold fog formed, the request to relative humidity is lower than warm fog. When advection fog formed the request to relative humidity is lower than radiation fog. The height of the fog top in Beijing is generally below 250 meters. When the fog occur , the wind is often still.This paper particularly analysis the macroscopic physical feature of a continual bad fog occur during November 30, 2004 to December 3 and two bad fog process detected by microwave radiometrics. Discovery that: Beijing is controlled by weak high-pressure ridge or is located at the bottom of low pressure tank when fog occurred. Dominating west air current, low altitude and ground are in the average Presses area. There is no obvious advection transportation when radiation fog occur, while, there are obvious southwest warm wet advection transportation when advection fog occur. Subtropical high press developed to the north and west, its position long-term maintenance can create advection fog which can continue several days. The inversion layer made the vital role to the radiation fog formation and the long time maintains. But, the inversion layer's existence does not have the direct function to advection fog's formation, its role is to maintain the fog for long time. The barometric steadily change make there is no Strong convection occur, the inversion layer cannot break through, the fog can maintain for long time.This paper chose anhydrous calcium chloride and sodium chloride as the contrast to RC/XW, the experiment on the capability of the three kinds of agent is done in the laboratory. The peak value diameter of RC/XW is 12μm; we crushed anhydrous calcium chloride and sodium chloride into four different scales: 10μm, 15μm, 20μm, 30μm. The conclusions are as followed. There is very big difference in the fog dissipation effects of different kinds of agent or the same kinds but different scales agent. The fog dissipation effect of agent is direct relative to its spread dosage. The RC/XW is suitable in dissipation warm fog that water content is more than 0.3 gm-3, which can seriously influence the Line-of-sight distance, and the spread dosage must be bigger than 1 gm-3.
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