How does a ice crystal make us better understand the environment and climate?

There was a fluffy, soft cloud that appeared on the day, and no one could hold back this moment without holding up the mobile phone. In the sky, we knew that there was a heavy rain. From an early age, the rain told us that the rain dropped from the clouds, but do you know what the clouds have become rain?

The accumulation of fog and the transmission of light forms black clouds (Picture Source: Wikipedia Encyclopedia)

The cloud is a collection of a large amount of tiny water droplets and ice crystals in the air. Although the cloud is composed of water, it is difficult to get bigger because the water droplet has surface tension, so it is difficult to fall from the cloud. Even if the "head" is a bit larger, it will quickly evaporate after falling out of the clouds and turns into water vapor. Then return to the cloud again. Compared with water droplets, ice crystals are easier to escape from the clouds and fall to the ground to form precipitation. Therefore, the formation of ice crystals is essential for precipitation.

How does the ice crystal form? When we only see the beautiful appearance of the ice crystal, what kind of reaction is they internal?

How is the beautiful ice crystal formed?

Maybe it is difficult to observe the naked eye, but the ice crystals under the microscope are really delicate and beautiful. Generally speaking, the formation of ice crystals can be divided into two ways: one is that water drops or cloud droplets directly form ice crystals; the other is that water vapor or too cold water droplets occur under the action of particulate matter or freeze to form ice crystals. The key substance that can trigger ice crystals is the ice nucleus particulate matter.

Ice crystal in the atmosphere (picture source: Snowcrystals)

Generally speaking, the first way requires that it can only occur below-38 degrees Celsius. This is difficult to achieve in the actual atmospheric conditions. Therefore, ice crystals are generally formed through the second way, that is, formed with the help of ice nucleus particles formed Essence

What kind of particles can be used as ice core particles? In fact, the floating dust, bacteria, and even pollen in the air are all ice nuclear particles with very strong ice nuclear activity. The dust here mainly refers to mineral particles. One of the ice core particles.

Mineral particulate matter and non -homogeneous reactions

Mineral particles that enter the atmosphere from drought and semi -arid areas have a significant impact on air pollution, human health, and climate change. In the process of floating in the atmosphere, the mineral particles are very easy to adsorb the pollution gases in the atmosphere due to its large surface area and react with it. The reaction process of this gas on the surface of the particles is called non -average reaction.

At present, studies have shown that the non -average reactor of mineral particles and nitric oxide plays an important role in the removal of nitrogen oxides, the formation of ozone and nitrate, which significantly affects air quality. However, we still don't know what impact of the non -average reaction of nitric oxide on nitric oxide on the ice nuclear activity of mineral particles.

Severe air pollution incidents caused by mineral particulate matter Sandstorms (Picture Source: Wikipedia Encyclopedia)

In order to explore this issue, we have developed a method of determining atmospheric granules. The influence of activity.

The mineral particles we have selected are potassium long stone and Arizona sand dust. Among them, potassium long stone is currently considered mineral particles with strong ice nuclear activity, and Arizona sand dust is a substitute for natural sand dust particles because it has already had already already already The advantages of knowledge of particle size distribution, mineral composition, and simple acquisition channels are widely used internationally.

The influence of the non -equalization of nitric dioxide in the opposite opposite response of the minerals ice nuclear activity (picture source: authors self -made)

We found that non -average reactions of nitric oxide can significantly reduce the ice nuclear activity of long stones and Arizona sand dust. Specifically, during the reaction of 0 to 6 hours, the surface of the long stone particles gradually increased due to the increase in the reaction time due to the increasing reaction time due to non -average reaction. Increase and gradually decrease. However, when the response time was further extended to 24 hours, the nitrate content and ice nuclear activity of the long stone did not change significantly.

For Arizona sand dust, we found that during the reaction 0 to 24 hours, the nitrate content of Arizona sand dust gradually increased with the increase in the reaction time; at the same time, its ice nuclear activity gradually decreased. In addition, we also found that there is a significant difference in the impact of non -average of nitric dioxide and the effects of Arizona sand dust.

Who affects the ice nuclear activity of mineral particulate matter?

How is the non -preliminary reactions of nitric dioxide reduced the ice nuclear activity of these two mineral particles? If you want to answer this question, you need to understand what special properties make mineral particles have strong ice nuclear activity.

At present, research has found that the surface properties of the surface shape, lattice structure, and surface -oriented group of mineral particles are closely related to the ice nuclear activity of the particulate matter. For example, a study published in Science found that the formation of ice crystals usually occurs at the defects and cracks on the surface of the mineral particles.

Due to the lack of perception of mineral granules, we cannot accurately answer why non -balanced reactions can reduce the ice nuclear activity of mineral particles. But here, we tried to propose the following mechanism to explain: During the non -homogeneous reaction period, nitric oxide will react with the surface of the mineral particulate matter, and replace the potassium, sodium, and aluminum in the structure of the mineral particles in the mineral particles, which will change the minerals to change the minerals The lattice structure of the particle material is reduced to reduce its ice nuclear activity. On the other hand, non -average interpretation will change the hydroxyl -based energy group on the surface of the particles, which will affect the surface properties of the particulate matter, thereby reducing its ice nuclear activity. So far, scientists still cannot perfectly answer the micro physical processes and influencing factors formed by ice crystals in the atmosphere, but continuing to explore these issues will have an important role that we can understand the environment and climate effects of atmospheric particles in the future.

Produced: Popular Science China

Production: Chen Lan Xia Di Tang Mingjin (Guangzhou Institute of Geochemistry, Guangzhou Academy of Sciences)

Producer: China Science Popularization Expo

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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