The atmosphere It is the gas layer that surrounds the Earth's surface. It is formed by a mixture of gases that we call air.
In astronomy, we call atmosphere to a mixture of several gases surrounding any celestial object, such as the Earth, when it has a gravitational field sufficient to prevent them from escaping.
On Earth, the current mixture of gases, air, has developed over 4.5 billion years. The original atmosphere must have been composed solely of volcanic emanations, that is, a mixture of water vapor, carbon dioxide, sulfur dioxide and nitrogen, with hardly any trace of oxygen, very different from today.
Throughout this time, various physical, chemical and biological processes transformed that primitive atmosphere until leaving it as we now know it. The most important was carried out by algae and vegetables.
For living beings, especially for animals, the atmosphere is important because it houses the amount of oxygen we need to live. In addition, it filters the sun's rays that would be lethal to life and protects the Earth's surface from many external space agents, such as small meteorites.
In addition to protecting the planet and providing the gases that living things need, the atmosphere determines weather and climate.
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