Why was the ozone layer badly damaged between 1950 and 1990?

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Analysis: The trade name of chlorofluorocarbons, the refrigerant used in air conditioners and refrigerators, is Freon. Chlorofluorocarbons are stable in the lower atmosphere and linger for about 10 years into the stratosphere until they pass through the ozone layer.

After penetrating the ozone layer, under the action of strong ultraviolet rays, chlorofluorocarbons decompose rapidly, producing chlorine atoms, which are extremely active and specially dismantle ozone molecules, causing the ozone layer to gradually thin and appear hollow.

More than 15 million tonnes of chlorofluorocarbons (CFCs) have been released into the atmosphere. Only some of the HCFCs that enter the atmosphere are involved in the depletion of the ozone layer, and most of them are still wandering in the atmosphere, so that although the production and use of HCFCs have ceased in many places, the ozone layer will continue to be destroyed. What's more, in addition to chlorofluorocarbons, industrial exhaust gases, automobile and aircraft exhaust gases, nuclear products, and ammonia fertilizer decomposition products, which may contain nitrogen oxides, carbon monoxide, methane and other dozens of chemicals, are all factors that destroy the ozone layer.

The main cause of ozone layer depletion is the emission of chemicals produced by human activities, especially chlorofluorocarbons. These compounds include chlorofluorocarbons (CFCs), halonalkanes (halons), fluorocarbons (HCFCS), etc., which are mainly used in industrial applications such as refrigerants, solvents, foams, fire extinguishing agents, etc.

These compounds can enter the atmosphere and react in the upper atmosphere, releasing chlorine and fluorine atoms. These free radicals react with ozone molecules, destroying them and causing dilution and thinning of the ozone layer. This phenomenon is known as the ozone hole.

The formation and change of the ozone hole is also affected by a series of natural factors, such as solar radiation, climate change, seasonal changes, etc. However, chemicals emitted by human activities are a major contributor to the destruction of the ozone layer. In order to protect the ozone layer and the earth's environment, the international community adopted the Montreal Protocol to prohibit the use and production of ozone-depleting substances, and certain results have been achieved, and the rate of ozone layer depletion has been controlled to a certain extent.

The destruction of the ozone layer is mainly due to the thinning of the ozone layer above the Earth due to the large amount of chlorofluorocarbons (CFOs, refrigerators, air conditioners, freon-22, etc.) emitted into the atmosphere by humans.

Although the "three poles" of the earth (the Arctic region, the Antarctic region and the Qinghai-Tibet Plateau) are sparsely populated due to the harsh natural conditions and the limited amount of chlorofluorocarbons emitted into the atmosphere by local people, it has been observed that the odorous oxygen call layer is now more damaging over the region.

This is mainly due to the low altitude of the ozone layer in the region.

We know that the earth's atmosphere is divided into five layers: troposphere, stratosphere, mesosphere, thermosphere and outer layer; The ozone layer is located in the stratosphere. The troposphere is the lowest layer, and harmful gases emitted into the atmosphere by humans are the first to enter. Its height is the top that can be reached by the convective movement of the air in this layer, and its height varies with latitude and topography; The troposphere is high in the equatorial region due to the high solar radiation and strong air convection movement. The polar regions have less solar radiation and weaker air convective movement and lower troposphere. The South Pole is colder than the North Pole and therefore has a lower troposphere; Although the Tibetan Plateau is not very high latitude, due to its high topography as the "roof of the world", its surface temperature is lower, and the air convection movement is not strong enough, so the troposphere is also low.

It is precisely because the troposphere over the "three poles" is also low that the corresponding stratosphere height is also reduced. The chlorofluorocarbons emitted into the tropospheric atmosphere will reach the sky above the "three poles" with the circulation of the atmosphere, and it is precisely because the stratosphere of the "three places" is low, so the chlorofluorocarbons can reach the stratosphere and destroy the ozone layer, forming an ozone hole.

The actual observation is also the same, the ozone layer depletion in the Arctic region is less than that in the Antarctic region, and the ozone layer depletion in the Tibetan Plateau is less than that in the Arctic region.