Six questions to understand "artificial rainfall": Why is it not "artificial rainfall"?

Since July, there have been continuous high temperature and rainy weather in southern my country, and drought or even drought in some areas. In the past few days, the meteorological departments across the country have seized the opportunity of the weather and actively carried out artificial rainfall operations.

(Picture source: National Climate Center)

Some netizens asked: "For so long temperature for such a long time, why can't we keep raining and cooling all the time?" "Does artificial rainfall and sowing catalyst affect the environment?" Today, we introduced it with 6 small problems and let's take a plate of manual rainfall. Things.

One question: What is artificial rainfall? Why isn't it "artificial rainfall"?

Before understanding artificial rain, we first need to know -where is the rain come from?

Rain is the water droplet landed from the cloud. The water on the land and the ocean surface evaporates into water vapor. After the water vapor rises to a certain height, it will become a small water droplet. These small water droplets form the cloud. It became a large water droplet. When it was so large that the air couldn't hold it, it fell from the clouds, forming rain.

Therefore, in order to form rainfall, three conditions must be met. Water vapor in clouds, rising air flow, and sufficient coagulation tuberculosis or ice nuclear nuclear.

(Picture source: China Meteorological News)

Artificial influence weather (manual rainfall is one of them) means to avoid or reduce meteorological disasters and reasonably use climate resources. Under appropriate weather conditions, the physical and chemical processes of local atmosphere are artificially influenced by scientific and technological means to achieve rainfall raindrops. (Snow), hail, rain, eliminate rain, fog, frost and other purposes.

(Picture source: China Meteorological News)

Artificial rainfall does not mean artificial rainfall. The role of catalysts is like "brine tofu", but the premise is that "brine" can order tofu, that is, the weather has met the basic conditions of rainfall (abundant water vapor, rising airflow movements ), Artificial rainfall can play a role.

Second question: How to "increase" artificial rainfall?

Since ancient times, people have fantasized the weather. The "Guangyang Miscellaneous Ji" in the Qing Dynasty in China contained: "In the summer and June, there were often storms, and Huang Yun came from the mountains. There must be hail. Switching, that is, it ’s scattered." It means that in the summer, there are often storms. When the ancients saw the yellow clouds rolling, they shot drums and shot it with a cannon to the sky, so that the yellow cloud gas was spread out to achieve the effect of hail prevention. This is a vivid description of the ancient Chinese artillery hail.

It can be seen that the working people in our country have long had the idea and practice of human intervention in the weather, but due to the backwardness of science and technology at that time, these practice ended in failure.

At present, our manual rainfall method is to increase the tuberculosis by spreading catalysts to the cloud, such as salt powder, dried ice or silver iodide, etc., and can also use sound waves, femtosecond lasers, charged particles and other means to promote hydrophilic condensation. Clouds touched and increased the transformation of clouds and rain to form precipitation falling to the ground.

In order to cope with high temperature and dry weather, the meteorological department of Yichang City, Hubei carried out artificial rain increase operations (text/picture source: Tang Qiaozhen, Leng Pengfei, Wang Yan)

Three questions: How to send "catalyst" to the cloud?

How to send a catalyst to the cloud? This depends on the "explosive" equipment in the weather operation! In terms of rainfall operation methods, the conventional is to sow the clouds and sprinkle catalysts to the cloud through aircraft, high guns, rockets, and ground burning furnaces.

Burning furnace with ground: Generally speaking, ground burning furnaces are mainly used in mountainous areas with inconvenient transportation or areas that are more difficult to apply for operating airspace. The operators send artificial ice nucleus into the clouds through the flames containing catalysts.

Ground Burning Furnace Device

Use of aircraft: Aircraft operations can carry catalysts and sowing devices or mount aircraft flame launch systems according to different cloud layers conditions and needs, and rain increase operations at the appropriate cloud layer location. In addition, the aircraft can also be loaded with the observation of cloud micro -structures and tracking and monitoring of changes in Yunhong and micro -state before and after catalysis. The aircraft operation is strong, the area of ​​catalysis is large, and the rainfall effect is good.

The shadow (artificially affected weather) plane in the homework

High guns/rockets: high guns and rockets have poor maneuverability relative to the aircraft, suitable for operating in fixed target areas (such as water increase for reservoirs), especially to catalyze the flowing clouds that are threatened by aircraft flight safety.

Shadow cannon

In general, when the catalyst is successfully delivered to 15 minutes to 20 minutes, the effect of rainfall is obvious.

In my country, the implementation of manual affecting weather activities must strictly abide by relevant laws, regulations and specifications, and abide by the strict manual affecting weather operation standards. For artificial rainfall, aircraft, rockets, and artillery must apply for operational airspace before rain increase operations, and strictly launch artificial rainfall rockets and shells in the approved airspace to ensure operation safety.

(Picture source: China Meteorological News)

Fourth question: It depends on the "cloud" policy to increase artificial rain?

When it comes to this problem, it is necessary to mention a concept. The original clouds were divided into "cold and warm". Due to the different precipitation mechanisms of the cold cloud (the temperature in the clouds below 0 ° C) and the warm cloud (the temperature in the clouds above 0 ° C), the clouds with different "cold and warm" rain increase the rain, and the catalysts used are also different.

For the artificial rainfall of Lengyun, the traditional method is usually to sow iodide, silver, and dry ice, etc., to increase the concentration of ice crystal in the cloud to make up for the lack of ice nucleus in the cloud, and to achieve the purpose of rainfall or increased rain.

(Picture source: China Meteorological Bureau Meteorological Propaganda and Science Popularization Center)

The artificial rainfall of the warm cloud is usually anecades with salt powder such as salt powder in the cloud, so that a number of large cloud droplets can be formed quickly in the cloud. The weight "increased, and the support of the rising airflow finally couldn't resist the role of gravity, so it had to fall down to form rainfall. (Picture source: China Meteorological Bureau Meteorological Propaganda and Science Popularization Center)

Five questions: High -temperature days, why can't we keep raining and cooling all the time?

Wishes are beautiful, but artificial rainfall does not want to increase!

First of all, there is rain with rain, but not all clouds have precipitation potential. The cloud of artificially raining needs to meet three conditions, and the thickness of the cloud layer is greater than 2 kilometers; water vapor must be charged in the cloud; Generally speaking, the accumulated clouds and layers of clouds are not easy to produce precipitation, while the accumulated rain clouds (hybrid clouds coexisting in ice water) are more conducive to the growth of cloud droplets to raindrops.

Therefore, some time ago, it continued to be high temperature. Chongqing and other places were "clear in the sky, no clouds", and naturally did not meet the conditions for artificial rainfall.

On August 25, the China Meteorological Administration affects the weather center and the Sichuan Provincial Meteorological Bureau to call two large drone organizations to implement manual rainfall operations, with an operating area of ​​6,000 square kilometers (picture source: CCTV News)

Six Questions: Will artificial rainfall work pollute the atmosphere? Will it bring a climate chain reaction?

In fact, the catalysts adopted by artificially affect weather operations are mainly dry ice (solid carbon dioxide), liquid nitrogen, silver iodide, etc. These catalysts have high ice -forming capabilities, and each job only requires a small amount.

In terms of commonly used cold cloud catalysts, dried ice and liquid nitrogen vaporization have become carbon dioxide and nitrogen -all are the main components of air, so they are "ecological safety catalysts", of course, they will not pollute the environment. In addition, long -term monitoring found that the amount of silver iodide used in the aircraft and the artificial affecting weather operations of the aircraft was very small, and the concentration of silver ions accumulated in the water body and soil in the operation area was far lower than the concentration stipulated by the World Health Organization.

Therefore, the correct use of artificially affect weather catalysts will not cause environmental pollution.

So, will artificial intervention bring climate chain reactions?

In fact, the earth's water circulation system is weekly. The air resources in the air are mainly distributed in the atmosphere of the stream.

Global hydrological cycle schematic diagram. (Picture source: World Meteorological Organization)

According to the conditions and processes formed by cloud water resources in the air, it is a renewable resource, and artificially affects the small and medium standards of tens of kilometers, which will not affect the entire climate system.

Produced: Popular Science China

Author: Liu Dan, Zhang Juan Zhang Ge Miao (China Meteorological News)

Producer: China Science Popularization Expo

Expert Consultant: Yao Zhanyu, a second -level researcher at the China Meteorological Administration's artificial influence of weather center

Picture source: Except for indication, other pictures are photographed by Sun Nan, Li Gen, and Qinghai Meteorological Bureau

Review: Duan Haoshu Ye Haiying

The China Science Popularization Expo is the Science Popular Science Platform of the Chinese Academy of Sciences. It is sponsored by the Computer Network Information Center of the Chinese Academy of Sciences. Relying on the high -end scientific resources of the Chinese Academy of Sciences, it is committed to spreading cutting -edge scientific knowledge and providing fun science and education services.

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