What is atmosphere?

The atmosphere is a layer of gases that surrounds the Earth and extends outward from the planet's surface. It is held in place by Earth's gravity and plays a crucial role in supporting life, regulating climate, and protecting the planet from harmful radiation.

The Earth's atmosphere is composed of various gases, primarily nitrogen (about 78%) and oxygen (about 21%), along with smaller amounts of other gases such as argon, carbon dioxide, neon, helium, and hydrogen, as well as water vapor and trace amounts of pollutants.

The atmosphere is divided into several layers based on temperature and composition, including:

1. Troposphere: The troposphere is the lowest layer of the atmosphere, extending from the Earth's surface up to an altitude of about 8 to 15 kilometers (5 to 9 miles) at the poles and 18 kilometers (11 miles) at the equator. It contains the majority of the atmosphere's mass and is where weather phenomena such as clouds, precipitation, and atmospheric mixing occur.

2. Stratosphere: The stratosphere lies above the troposphere and extends up to an altitude of about 50 kilometers (31 miles). It contains the ozone layer, which absorbs and scatters ultraviolet (UV) radiation from the Sun, providing protection against harmful UV rays.

3. Mesosphere: The mesosphere is located above the stratosphere and extends up to an altitude of about 85 kilometers (53 miles). It is characterized by decreasing temperatures with altitude and is where meteors burn up upon entering the Earth's atmosphere.

4. Thermosphere: The thermosphere lies above the mesosphere and extends up to an altitude of about 600 kilometers (373 miles). It is characterized by high temperatures due to the absorption of solar radiation, but the air density is extremely low.

5. Exosphere: The exosphere is the outermost layer of the atmosphere, extending from the thermosphere out into space. It consists of a thin layer of hydrogen and helium gases and gradually transitions into the vacuum of space.

The Earth's atmosphere performs several important functions, including regulating the planet's temperature, distributing heat and moisture, supporting weather patterns, and protecting life from harmful solar radiation and cosmic rays. It is essential for sustaining life on Earth and maintaining the delicate balance of the planet's ecosystems.