What are the dangers of artificial rainfall

Artificial rainfall is a scientific technology that uses airplanes or rockets to spread catalysts into clouds to increase the amount of precipitation or the amount of precipitation. In fact, the scientific pronunciation of artificial rainfall is artificial rainmaking, because the so-called artificial rainfall means that when the original cloud layer grows to a certain size, it can make the cloud layer rain. Although this kind of artificial rainfall can bring us rain, it also has certain hazards. This article will introduce the principles, conditions, methods and hazards of artificial rainfall.

1. Principle

Artificial rainfall uses the principles of cloud and precipitation physics. By spreading precipitation agents (such as salt powder, dry ice or silver iodide) into the clouds, the cloud droplets or ice crystals are enlarged to a certain size and then fall to the ground to form precipitation. The microphysical process of artificial cloud influence can, under certain conditions, stimulate clouds that are not able to precipitate naturally to precipitate. It can also improve the precipitation efficiency and increase the precipitation of clouds that have a large water supply and are often able to precipitate naturally. However, clouds that cannot produce precipitation naturally can supply less water, so the economic value of artificial catalysis is limited.

2. Conditions

There are two conditions for the formation of precipitation: one is that there must be sufficient water vapor in the clouds, and the other is that there must be an appropriately large number of condensation nuclei. Therefore, the method of artificial rainfall is to introduce artificial condensation nuclei into the clouds. The catalyst is usually delivered into the cloud using aircraft, rockets, anti-aircraft guns, balloons, and by burning silver iodide on the ground in areas of updraft. For warm clouds with temperatures above zero, hygroscopic substances such as salt powder, urea, calcium chloride, etc. are generally used to turn the water vapor in the clouds into large water droplets that fall as rain. For cold clouds with temperatures below zero degrees, artificial crystal nuclei such as silver iodide or dry ice, liquid nitrogen, etc. are spread to increase the number of ice crystals in the cold clouds and improve precipitation efficiency.

3. Methods

Artificial rainfall is generally achieved by sending catalysts into the clouds using aircraft, rockets, anti-aircraft guns, balloons, and by burning silver iodide on the ground in areas of rising air currents. Aircraft usually fly to an altitude of about 6,000 meters to penetrate the clouds and spread catalysts. Rockets and anti-aircraft guns directly bombard appropriate parts of thunderclouds, and warheads loaded with silver iodide are sent into the clouds. A silver iodide flare bomb is hung under the balloon, which rises into the cloud layer above zero degrees and burns, releasing the catalyst.

4. Hazards

At present, my country mainly uses two types of catalysts for artificial rainfall. One is dry ice, which cools the surrounding air layer to dozens of degrees below zero when vaporized, thereby causing the condensation of water droplets. The second type is silver iodide, which has excellent ability in making rain. Dry ice is actually carbon dioxide, and silver iodide, as a chemical substance, has extremely low toxicity. In addition, silver iodide is very efficient in producing ice crystals. Usually, it only takes a dozen grams or dozens of grams to make a cumuliform cloud. The amount dropped is very low and almost negligible, so it will not cause any pollution.