Conditions and utilization of artificial rain suppression?

Artificial precipitation enhancement is a large-scale and large-scale artificial precipitation enhancement operation in the upper reaches of the precipitation cloud system, which accelerates the diffusion of energy in the weather system, and at the same time makes water droplets form quickly in advance and land on the ground in advance. This way can make some precipitation fall ahead of schedule, thus ensuring the scheduled good weather.

Artificial rain suppression

There are two conditions for precipitation: ① there should be enough water vapor in the cloud, and ② there should be an appropriate number of condensation nuclei. Therefore, the method of artificial rainfall is to introduce artificial condensation nuclei into the cloud. Generally, aircraft, rockets, anti-aircraft guns, balloons and ground burning silver iodide in the updraft area are used to send the catalyst into the cloud. Planes usually fly to an altitude of about 6000 meters and spread catalysts through clouds. Rockets and anti-aircraft guns directly bombard the appropriate parts of thunderstorm clouds, and the warheads are loaded with silver iodide and sent into the clouds. A silver iodide flame bomb hung under the balloon rose above 0℃ in the cloud and burned to release the catalyst. Generally, it is hygroscopic substances such as salt powder, urea and calcium chloride. Used for warm clouds above zero, so that the water vapor in the clouds becomes big water and drops into the rain. For Leng Yun where the temperature is lower than 0℃, artificial crystal nucleus silver iodide, dry ice and liquid nitrogen are sown to increase the number of ice crystals in Leng Yun and improve the precipitation efficiency.

The principle of artificial rain suppression is similar to that of artificial rainfall, but there are some differences. There are two ways of artificial precipitation enhancement: ① artificial precipitation enhancement is carried out on the windward side of the target area, which is generally about 60~ 120 km, so as to end the rainfall ahead of schedule; (2) In the windward direction of the target area, usually at a distance of about 30~60 kilometers, the ice cores are excessively sown into the clouds, so that the ice core content reaches 3~5 times of the precipitation standard. If there are more ice cores, each ice core absorbs less water and cannot form enough raindrops. In general, it is to let the rain "hold on".

With regard to the general process of artificial rain suppression, we should first carefully observe and predict the weather conditions and their changing trends to determine whether there is a possibility of rain. If it is found that there is a possibility of rain, it is necessary to further understand the possible influence trend of this weather system on the local area, as well as the possible time and place. After that, it is necessary to formulate an artificial rain suppression plan for the protected area. Once the operational conditions are met, the aircraft, ground rockets and anti-aircraft guns will be started immediately for combat. If it is affected by the mobile weather system, artificial precipitation enhancement should be carried out in the upstream area of the proposed protected area, so that the local rainfall that may occur in the upstream area will land ahead of time, so as to slow down or eliminate the rainfall in the proposed protected area; If the local cloud system develops to produce rainfall, it is necessary to over-broadcast the target cloud system to fully "eat" the water in the cloud, so that it is difficult for cloud droplets to grow into raindrops and land on the ground, thus reducing or eliminating rainfall.

On August 8, 2009, at the opening ceremony of the Beijing Olympic Games, when gorgeous fireworks lit up the sky over Beijing, meteorologists carried out the largest weather modification operation in China, turning a rainstorm cloud belt from the southwest into invisible, which laid a solid foundation for the success of the opening ceremony.

The Olympic Games adopted the method of artificial rain suppression by aircraft, mainly aimed at relatively stable layered clouds, among which, layered clouds are divided into Leng Yun and warm clouds. For Leng Yun, silver iodide can be carried by plane and carried out catalytic operation in the cloud; If it is warm cloud, a hygroscopic warm cloud catalyst is used. For convective clouds that are prone to lightning, rockets are used to artificially eliminate rain.

On the afternoon of the opening ceremony, the meteorological department sent four planes to detect clouds and precipitation respectively and carry out warm cloud catalyst operation; The rocket ran from 6 pm to 1 1: 30, lasting about five and a half hours, and * * * launched 1 104 pieces.

But at present, the impact of artificial rain suppression is relatively limited. It will achieve ideal results for small-scale and weak precipitation weather processes, but in the case of heavy precipitation weather processes, the current technical means can not achieve the ideal effect of artificial precipitation elimination.