Why is the atmosphere formed and how is it formed?

Generally speaking, it is believed that the evolution of the earth's atmosphere has roughly gone through three processes: the primitive atmosphere, the secondary atmosphere, and the present atmosphere.

Originally, during the formation of the Earth, it moved around the sun while absorbing dust and gases in its orbit. When the Earth's surface gradually condenses into a solid state, it is surrounded by a layer of atmosphere, which is the primordial atmosphere, and its main components are hydrogen and helium.

Because the earth's crust is still unstable and volcanic activity is frequent, the gases emitted by volcanoes form the Earth's secondary atmosphere. Its composition is mainly methane and hydrogen, with some ammonia and water vapor, but there is still no oxygen.

The formation of oxygen is the main indicator of the formation of the modern atmosphere, and its formation process is closely related to the emergence and development of life on Earth. The first life appeared in deep water that could not be reached by the sun's ultraviolet radiation, and then gradually moved to shallow water, and then developed into chloroplasts, and the photosynthesis of green plants became the most important cause of oxygen formation in the atmosphere.

The increase of oxygen forms an ozone layer at high altitude, which absorbs ultraviolet rays, which is conducive to the rapid reproduction and development of plants on the earth, and greatly increases the content of oxygen and carbon dioxide in the atmosphere on the earth, and forms the current atmosphere after billions of years.

When the Earth was first formed, the main components of the atmosphere were carbon dioxide, methane, hydrogen, ammonia and water vapor, but after a series of changes caused by chemical and biological factors over a billion years or so, the composition of the atmosphere today is mainly nitrogen and oxygen.

As the Earth takes shape and is slowly cooled by high temperatures, a large number of bubbles are mixed with water vapor to form a cloudy atmosphere. Most of these clouds later formed raindrops that continued to fall, forming the first oceans. After the heavy rain, the sun's rays had more chance to reach the bottom of the atmosphere as the clouds dispersed, so the methane and ammonia in the atmosphere were broken down by the sunlight, and most of the hydrogen released in the process escaped into space due to its own lightness, leaving behind carbon dioxide and nitrogen.

It wasn't until about 3.5 billion years ago that the earth had primitive organisms (archaeozoic blue-green algae) that could do photosynthesis, and since the existence of these organisms, the carbon dioxide in the atmosphere has been replaced by oxygen through photosynthesis, and some of this oxygen has been released to the upper altitude, gradually forming today's ozone layer. Later, organisms evolved into a group of people who respirated, and the carbon dioxide and oxygen content in the atmosphere continued to replace each other, seesawing, and it was not until about 1 billion years ago that the ratio of carbon dioxide and oxygen in the atmosphere gradually evolved into a pattern similar to the current atmospheric composition.

Therefore, in general, the atmosphere today mainly contains nitrogen, oxygen, water vapor and carbon dioxide. At the beginning of the formation of the earth, carbon dioxide, methane, hydrogen, ammonia and water vapor were the main gases in the atmosphere, and these changes were caused by a series of chemical changes caused by the cooling of the earth, and later the emergence of photosynthesis and respiration organisms.

The Earth's atmosphere is the formation of an atmosphere of thousands of kilometers under the gravitational pull of the earth, when a large amount of gas gathers around the earth.

The density of the gas becomes thinner and thinner as the height above the ground increases. Sounding rockets still found a rarefied atmosphere at an altitude of 3,000 kilometres, and it is suggested that the upper limit of the atmosphere may extend to about 6,400 kilometres above the ground.

The mass of the atmosphere is about 6,000 trillion tons, which is almost one millionth of the total mass of the Earth. According to the volume fraction of various gases in the atmosphere, its main components include: nitrogen 78%, oxygen 21%, argon, carbon dioxide neon, in addition to water vapor and dust.

From the surface upwards, the atmosphere is usually divided into five layers: troposphere, stratosphere, mesosphere, thermosphere and exosphere.

One of the main reasons why millions of things can survive on top of the earth is because of the thin atmosphere that surrounds our planet! So how exactly is our planet's atmosphere formed? The atmosphere of our planet is neither as dense as Venus nor as thin as Saturn!