The earth's atmosphere can be divided into five layers: troposphere, stratosphere, mesosphere, thermosphere and outer atmosphere. The place with the highest concentration of stratospheric ozone is called the "ozone layer". The thickness and content of ozone layer will change with latitude, season and weather, and the content of ozone layer varies greatly in different regions.
Ultraviolet rays and all kinds of radiation from space will be absorbed by ozone, which will protect the living things on earth from ultraviolet rays and maintain the temperature to a certain extent. The lethality of ultraviolet rays filtered by the ozone layer is greatly reduced, and the remaining small amount of ultraviolet rays does little harm to organisms after entering the earth, but can help organisms kill bacteria, so the existence of the "ozone layer" is very important to organisms!
For a time, the "ozone hole" caused great repercussions in the international community and triggered a series of environmental problems. Some scientists believe that the biggest reason for ozone depletion is that chlorofluorocarbons made by humans enter the atmosphere, which prevents the formation of ozone. Therefore, many countries have begun to restrict the use and production of chlorofluorocarbons. Today, we can find that almost no one has mentioned the hole in the ozone layer in recent years. Why? Has the hole in the ozone layer healed?
Facts have proved that the ozone hole in the earth's north and south poles is indeed shrinking, and human beings have indeed played a great role in limiting the emission of harmful chlorofluorocarbons. The ozone hole over 20 19 Antarctic has been reduced to the smallest size in recent years, and the contribution of human beings to the recovery of the ozone hole can not be ignored.
In fact, the appearance of ozone hole can't be entirely attributed to human beings. The appearance of Antarctic and Arctic ozone holes shows seasonal changes, and huge ozone holes often appear in winter, which proves that the nature of ozone holes is a natural phenomenon. The harmful gases emitted by human beings can indeed prevent the birth of ozone, but the activities of the sun will also have an impact on the ozone layer, and the climate and atmospheric changes of the earth will also have a certain impact on the ozone hole.
1987, major industrialized countries signed the Montreal convention, and since then, the ozone layer problem has been solved. At present, it is generally believed that the ozone hole will no longer pose a threat to human beings and will not be mentioned for a long time.
The earth has the most unique atmosphere of all the planets in the solar system, but when the earth was just born, the oxygen content in the earth's atmosphere was very low and almost non-existent. The earliest life on earth is "anaerobic life", and these creatures can survive without oxygen. This situation lasted for many years, until the "first great oxidation event" occurred, and the oxygen in the earth's atmosphere began to increase slowly.
The occurrence of large-scale oxidation events is closely related to the appearance of "cyanobacteria". Cyanobacteria are not algae, but an ancient prokaryote. Cyanobacteria are the earliest organisms that can carry out photosynthesis. After birth, cyanobacteria began to multiply in large numbers, and the oxygen in the earth's atmosphere began to increase. Coupled with the movement of the continental plate, the emission of greenhouse gases such as methane in the ocean has decreased. The abundance of oxygen has laid a good foundation for the complex evolution of life. Of course, besides oxygen,
"Ozone" is a naturally occurring greenhouse gas. The sun has been emitting a lot of radiation into the universe. When ultraviolet rays reach the earth, they will first meet the atmosphere. When oxygen molecules in the upper atmosphere meet ultraviolet rays, they will decompose into oxygen atoms, and then oxygen atoms and oxygen molecules will react again to become ozone.
Because ozone is heavier than oxygen molecules, it will fall downward after formation, and will rise again due to changes in temperature and atmosphere after reaching the ozone layer. When ozone is irradiated by long-wave ultraviolet rays, it will be reduced to oxygen, and the ozone layer will continue to produce new ozone, stop absorbing ultraviolet rays, and then become oxygen to rise again, maintaining a generally stable state.
If there is no harmful gas emitted into the air by human beings to prevent the formation of ozone, the ozone layer will remain stable for a long time and protect life on earth. At present, human beings have tried their best to reduce the emission of harmful gases, and the ozone hole has also been significantly reduced in recent years, so people don't mention the ozone hole.