How long does artificial rainfall usually last, and how much does it cost?

2020-09-03 | Science on the planet Original |

Artificial rainfall has become more and more common in our daily lives, and it has greatly benefited our lives. In fact, artificial rainfall should be called "artificial rainfall enhancement" to be precise.

Because according to human's current scientific and technological capabilities, it is not possible to achieve "growth of rain out of nothing". We can only change the amount of rainfall under the premise that there is a cloud layer rich in water vapor, which can make the rain with less rainfall become more rain.Change from moderate rain to heavy rain or heavy rain.

Required conditions for artificial precipitation:

1. Water vapor conditions, that is, at a certain altitude, it is best to have clouds rich in water vapor.

2. Ascending motion, because ascending motion will bring water vapor to high altitude to condense and form clouds water vapor continues to rise, first encounters heat and then meets cold, resulting in partial water vapor saturation and precipitation, this is the cloud we see, butOnly in this way can the conditions of precipitation be reached.

3. Sudden drop in temperature, in order for the water vapor in the clouds to condense into rain and fall down, there must be a sudden drop in temperature, such as using dry ice to instantly take away a lot of heat when it sublimates to reduce the ambient temperature to promote clouds and rain.

4. Condensation nucleus, which refers to the solid, liquid and gaseous aerosol particles that play a core role in the condensation process, because the condensation of water vapor requires an attachment. If there is no condensation nucleus, the water vapor cannot be effectively condensed.

5. Sufficient ice crystals, the water droplets in the cloud are very small and can be stably suspended in the air for a long time. If there are not enough ice crystals, the sky will only be in the state of clouds and no rain, and silver iodide particles will be sprayed into the cloud and fog.In order to produce enough ice crystals.

Artificial rain enhancement and natural rainfall are actually very similar, both rely on the condensation of water vapor in the clouds, and finally fall.

The principle of “artificial precipitation enhancement”

Artificial rain enhancement is based on the physical characteristics of different cloud layers, such as cloud thickness, height, water vapor content in the cloud, and temperature, etc., to choose the right time to spread dry ice into the cloud by means of airplanes, rockets, etc.Catalysts such as silver iodide and salt powder promote precipitation in clouds or increase precipitation, so as to achieve the purpose of precipitation.

Artificial precipitation is divided into warm cloud rainfall and cold cloud rainfall.

Warm cloud rainfall: As the name implies, a warm cloud is a cloud with a temperature higher than 0℃. To make the warm cloud precipitation or increase precipitation, it is necessary to sow the cloud with hygroscopic particles such as salt powder and urea, so that a large part of the warm cloud is obtained.Water droplets.

As the initiator of gravity collision collision and merging process caused by gravity, it destroys the original stability of the warm cloud and achieves the coexistence of large and small water droplets, and then the cloud droplets will rise, fall and mix in the atmosphereCollide with each other and merge into larger cloud droplets, forming precipitation.

Cold Cloud Rainfall: Cold clouds are clouds with a temperature lower than 0°C. For precipitation in cold clouds, airplanes and other catalysts such as dry ice and silver iodide are used to produce a large number of ice crystals in the natural cloud the formation of water vapor on the ice core by condensation growthThe density of ice crystals in the upper part of the cold cloud will increase, so as to promote or increase precipitation.

To sum up, there are two forms of artificial precipitation enhancement, but they all need to use airplanes and rockets to launch some catalysts to promote the condensation of water in the clouds as soon as possible.

The cost of artificial precipitation

The project of artificial precipitation enhancement is complicated, and the requirements for equipment and catalysts are relatively high. Therefore, the cost of artificial precipitation enhancement is certainly not low. To achieve rainfall, the first step is to release weather balloons to collect the cold and hot degrees of the clouds and establish rainfallmodel.

Because precipitation is divided into cold cloud and hot cloud, the formation mechanism is naturally different, so the catalyst used is also different, and the catalyst for hot cloud rainfall is salt, urea, etc., and the cost is relative to that of cold cloudThe price of dry ice and silver iodide is relatively low.

Secondly, the rockets, aircraft, and launch pads needed for rainfall are all money. For example, a rain bomb, that is, rockets and aircraft bombs range from 2,000 to 4,000 yuan, and the cost of the rocket launcher is even more amazing.200,000 yuan.

The initial cost of artificial rainfall was very high, and it was a waste of resources, but now the technology of artificial precipitation has become more and more skilled, but even if the technology of artificial precipitation is improving, artificial precipitation is still not a small amountCost.

Take the first implementation of artificial rainfall in Shanghai, my country, the cost reached 4.7 million yuan, of which catalyst costs for rainfall accounted for nearly one-tenth of the cost.

Since 1958, my country’s artificial precipitation enhancement experiments have achieved great results. For example, in 2016, my country’s artificial precipitation enhancement reached 61.5 billion tons in this year, which has contributed to agricultural production, ecological civilization construction, and disaster prevention and mitigation. contribution.

Under normal circumstances, artificial precipitation will last for about one hour, and it costs so much money for one hour. It sounds really painful! But artificial precipitation can effectively solve drought conditions, so artificial precipitation is beneficial and there areHarmful.


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