Structure of the Earth’s Atmosphere

The planet’s atmosphere is made up of different gases. The atmosphere helps make it possible for life to exist on Earth. In addition to giving us something to breathe, the atmosphere protects us from most of the harmful ultraviolet (UV) radiation from the Sun, warms the surface of the Earth by about 33° C (59° F) through the greenhouse effect, and keeps daytime and nighttime temperatures from being too different.

What is the atmosphere?

We all know that because there is life on Earth, it is different from other planets. Air is one of the things that makes it possible for life to exist on Earth. The air is made up of many different gases, and it surrounds the earth on all sides. The atmosphere is all the air around the Earth.

Composition of the atmosphere:

Major gases

Nitrogen (chemical symbol N2) is the most common gas in the atmosphere. It is mostly inert, which means that it doesn’t react easily with other substances to make new chemical compounds. Oxygen (O2) is the next most common gas. All living things on Earth, from humans to bacteria, need oxygen to breathe. Unlike nitrogen, oxygen reacts very quickly. Argon (Ar) makes up just under 1% of the atmosphere. It is an inert noble gas, which means that it doesn’t take part in any chemical reactions under normal conditions. Together, these three gases make up 99.96% of the air we breathe. The last 0.04 percent is made up of many different trace gases, some of which are important for life on Earth.

Important trace gases:

Carbon dioxide (CO2) affects the climate of Earth and is an important part of the biosphere, which is made up of all the living things on its surface. Only about 0.0325% of the air is made up of CO2. Plants need carbon dioxide for photosynthesis, the process by which they use sunlight to store energy as simple sugars. The molecules that make up these gases take in and send out infrared radiation, which we feel as heat. Most of the energy that comes from the sun is in the range of wavelengths that can be seen. Some of this radiation is taken in by molecules of greenhouse gases before it can escape into space, and some of it is then sent back toward the surface. In this way, these gases keep some of the heat from escaping and raise the temperature of the atmosphere as a whole. If there were no greenhouse gases in the air, the surface of the Earth would be about 90°F (32°C) cooler.

Aerosols

Aerosols are a group name for the many different kinds of airborne particles in the atmosphere. These particles can be liquid or solid, and they are so small that it may take a long time for gravity to pull them out of the air. Aerosols are things like suspended soil or desert sand particles, smoke particles from wildfires, salt particles from evaporated ocean water, plant pollen, volcanic dust, and particles made from pollution from coal-burning power plants. 

The sizes of the particles in aerosols are very different. The size of raindrops in a cloud is about 0.04–0.24 in (1–6 mm). Cloud droplets and fine desert sand can have sizes as small as 0.0004 in (0.01 mm). 

Structure of the atmosphere:

Based on the different temperatures and densities, the atmosphere can be split into five layers. These are:

1. Troposphere
2. Stratosphere
3. Mesosphere
4. The temperature (Ionosphere)
5. Exosphere

Troposphere

• It is the layer of the atmosphere that is the lowest.
• This layer is about 18 kilometres high at the equator and 8 kilometres high at the poles.
• At the tropopause, the temperature of the air is about –80°C over the equator and about –45°C over the poles. This area is called the tropopause because the temperature is almost always the same.

Stratosphere

• Just above the troposphere is the stratosphere.
• The lower part of this layer stays almost the same temperature up to a height of 20 km. After this, the temperature slowly gets warmer as the height goes up. In the top part of this layer, where there is ozone gas, the temperature goes up.
• Most of the UV rays from the sun are absorbed by this part of the stratosphere.

Mesosphere

• It is the third layer of air above the stratosphere.
• As you go up in altitude, the temperature in this layer starts to drop, going as low as -100 degrees Celsius at an altitude of 80 km.
• This layer is where meteors and falling stars happen.
• The mesopause is the top edge of the mesosphere.

Thermosphere

• Between 80 and 400 km above the mesopause is this layer.
• It is called the ionosphere because it is made up of ions, which are charged particles with an electric charge.
• Radio waves sent from the earth are reflected back to the earth by this layer, making it possible to broadcast radio.
• As you go up, the temperature here starts to rise.

Exosphere

• The exosphere is the layer of the atmosphere that is closest to space.
• There aren’t many gases in this sphere because there isn’t much gravity. Because of this, the density of the air here is very low.

Conclusion:

It not only gives us the oxygen we need to live, but it also keeps us safe from the sun’s harmful ultraviolet rays. It makes the pressure that makes liquid water possible on the surface of our planet. And it warms up our planet and keeps the temperature at a level where people can live on it.