The voluminous rain and snow that fell on the 13th have made townspeople pleasantly surprised. Though since the cloud layer was low and thin, anti-aircraft artillery could be launched to reach the cloud layer. The artificial inducement of the rain couldn't be implemented on schedule.
Zhang Xueshan of the office of artificially influencing the weather in Weishang, Shandong province explained that suitable weather conditions are required for inducing rain artificially. Adequate water resourced should exist in the clouds in the sky as well as appropriate rain force conditions. Only if these two basic conditions are filled, various kinds of rain inducing equipment could be transmitted inside the cloud level as a catalyst, producing the desired effect. This time, the air during the precipitation process was so severely cold, and the cloud thickness level didn't 'reach the standards'. Launching anti-aircraft artillery and rockets requires an angle of 45 degrees, as well as a cloud layer at an altitude of at least 3000 meters, but this time, with the course of cold air, the highest cloud level is only at 2000 meters, not reaching the favorable conditions for putting the man-induced precipitation into effect.
Zheng Xuesheng told reporters that the launching course cannot be realized, as anti-aircraft artillery in rockets cannot reach the inside of the cloud layer, the catalyst cannot have an effect, and might affect the safety of the inhabitants on the ground.
Staff members of the office for artificially influencing weather in Weishang have already prepared for artificial rain inducement two months ago, but tardily cannot put it into effect. In the course of the cold air communication this time, workers are constantly paying close attention to the weather situation since the dawn of the 13th, but the cloud layer conditions are completely unsatisfactory, the "lending water project" ultimately must be renounced.
Meteorologists explain, in order to indeed drop the sky's water to the ground, and not allow clouds to move out in vain, man-induced precipitation exists. Its can be achieved by two methods: "Inside the sky" and "ground surface operation". "In the sky" operation is using airplanes as a disseminating catalyst, "ground surface" operation is utilizing anti-aircraft weapons and rackets, launching them from the ground. Still, this doesn't mean that precipitation can be increased by as much as we want. Statistics show that using the man-made catalyst technology correctly can at most exploit 20% of the precipitation in the clouds.
According to what is understood, the principles of artificially induced rain can be summarized by these describing words: "Mechanism trigger". Even with the foundation of fully studying natural precipitation, man operation only triggers the natural rain mechanism. Rain can exist only if there are clouds, though not all clouds have a precipitation capacity. Only clouds with precipitation potential and the possibility of being utilized could be targeted by the rain catalyst.
On the dawn of the 13th, Shandong's Weifang city welcomes the first snow fall this winter. Reporters from Shandong's Weifang city's Weather Bureau has learnt, that by 19pm, December 13th, the mean precipitation in the entire city is 2.4 mm, highest precipitation in the district are of 4.8 mm. According to what is understood, the first snow fall in Weifang this year is late by 42 days compared to the winter last year. The precipitation this time has not been intervened by man and is natural precipitation.
 人工增雨 réngōng zēng yǔ - 'Man made rain increase', artificial rain inducing; Methods to induce precipitation when rain clouds appear, as explained in this article.
 潍坊市 wéifāng shì - Weifang city, a prefecture-level city in Shandong province.
 催化剂 cuīhuàjì - Catalyst, inducing factors
 气象 qìxiàng - Meterology