Composition and Structure of the Atmosphere

Composition and Structure of the Atmosphere: The atmosphere of the Earth is composed of Nitrogen (78%), Oxygen (21%), Argon (0.9%), Carbon dioxide (0.04%), and flicker gases. A varying amount of water vapor is also present in the atmosphere which is approximately 0.1% at sea level. The two important gases in the atmospheric composition are nitrogen and oxygen. About 99 percent of it is made up of these two gases. A few other gases that are still present in the our Earth’s atmosphere are argon, carbon dioxide, neon, helium, and hydrogen. In the upper atmosphere, the ratio of gases varies to the extent that oxygen is nearly nonexistent at 120 km altitude.

Let’s understand the Composition and Structure of the Earth’s Atmosphere.

What is the Earth’s Atmosphere?

The atmosphere is a mixture of gases that surrounds the Earth. It assists in making life possible by providing us Air to breathe, shielding us from harmful ultraviolet (UV) radiation coming from the Sun, trapping heat to warm the planet, and controlling extreme temperature differences between day and night.

Composition of Atmosphere Diagram

The composition of the atmosphere is as follows:

composition of the Earth’s Atmosphere – Digram

Composition of the Atmosphere

Earth’s atmosphere is composed of about nitrogen (78%), oxygen (21%), argon (0.9%), carbon dioxide (0.04%) and other gases. Flicker amounts of carbon dioxide, methane, water vapor, and neon are some of the other gases that make up the remaining 0.1 percent.

Many different gases are present in the atmosphere. In addition, it comprises a large amount of aerosols, which are both solid and liquid particles. At a height of 120 km, oxygen is almost nonexistent due to a change in gas proportions in the upper layers of the atmosphere. Similarly, water vapor and carbon dioxide are only present up to 90 kilometers from the earth’s surface.

Nearly 99% of the dry, pure air is made up of nitrogen and oxygen. Other gases, most of which are inert, make up around 1% of the atmosphere. Along with these gases, the atmosphere also contains significant amounts of water vapor and dust particles. These liquid and solid particles have major climatic consequences.

Different atmospheric elements and their unique properties are mentioned below:

1. Composition of the Atmosphere – Nitrogen

78% of the volume of the atmosphere is made up of nitrogen. It is a gas that is largely inert and an essential component of all organic molecules. Nitrogen primarily controls combustion via dilution of oxygen. Additionally, it indirectly supports several forms of oxidation.

2. Composition of the Atmosphere – Oxygen

Despite making up only 21% of the atmosphere’s total volume, oxygen is the most important gas. All living things breathe in oxygen. Additionally, oxygen has the ability to interact with other elements to create important substances like oxides. Additionally, without oxygen, burning is not possible.

3. Composition of the Atmosphere – Carbon dioxide

• Carbon Dioxide is the third significant gas and is a byproduct of combustion, although it only makes up around 3% of dry air.
• Through photosynthesis, green plants take carbon dioxide from the air and use it to create food and maintain other biophysical processes.
• Carbon dioxide is regarded as having major climatic significance since it is a powerful heat absorber.
• A key element of the heat energy budget is thought to be carbon dioxide.
• The amount of carbon dioxide in the atmosphere has been rising at an alarming rate due to the increased use of fossil fuels, such as oil, coal, and natural gas.
• More atmospheric carbon dioxide results in greater heat absorption. This might cause an abrupt climate change by drastically increasing the temperature at lower layers of the atmosphere.

4. Composition of the Atmosphere – Ozone

• Another important gas in the atmosphere is ozone, which is actually an oxygen molecule with three rather than two atoms.
• It is unevenly spread and makes up less than 0.00005 percent of the atmosphere’s volume.
• The highest ozone concentrations are seen at altitudes of 20 km to 25 km.
• It is produced at higher elevations and moved downward.
• Ozone is essential in preventing the sun’s harmful UV rays.
• Neon, helium, hydrogen, xenon, krypton, methane, and other gases are also present in the atmosphere, although in practically negligible concentrations.

5. Composition of the Atmosphere – Water Vapor

• Water vapor is the gaseous form of water that exists in the atmosphere.
• Life on earth is only possible because of the water vapor in the atmosphere, which also causes all precipitation.
• Its maximum concentration in the atmosphere is up to 4%.
• The highest concentration of water vapor is found in hot, humid locations, whereas the lowest concentration is found in dry regions.
• From low latitudes to high latitudes, water vapor concentrations typically continue to decline.
• In the same manner, its volume continues to shrink as altitude rises.
• Evaporation and transpiration are the two ways that water vapor enters the atmosphere.
• While transpiration draws moisture from plants, trees, and other living things, evaporation occurs in oceans, seas, rivers, ponds, and lakes.

6. Composition of the Atmosphere – Dust Particles

• Typically, dust particles are located in the lowest parts of the atmosphere.
• Sand, smoke, and sea salt are examples of these particles.
• In the atmosphere, sand particles play an important part. These dust particles support water vapor condensation.
• Around these dust particles, water vapor condenses into droplets during condensation.
• This process results in the formation of clouds and makes precipitation possible.

Structure of the Atmosphere

The atmosphere is comprised of layers based on temperature. These layers are – troposphere, stratosphere, mesosphere, thermosphere and exosphere.

Structure of the Atmosphere

1. Troposphere

• Around 80% of the mass of the entire atmosphere is found in the troposphere, which is the layer of the atmosphere closest to the earth.
• The troposphere’s temperature and water vapor content drop sharply with altitude.
• Because it absorbs solar energy and thermal radiation from the planet’s surface, water vapor plays an important part in controlling the temperature of the atmosphere.
• 99% of the water vapor in the atmosphere is found in the troposphere.
• Latitude affects the quantities of water vapor. They are highest above the tropics, where they can reach up to 3%, and get smaller as we get closer to the poles.
• Although turbulence may reach into the lower stratosphere, all meteorological phenomena take place in the troposphere.
• The name “troposphere” (which translates as “region of mixing”) refers to the rapid convective air currents that exist inside the layer.
• The tropopause, which is the layer’s upper boundary, has a height that varies from 5 miles (8 km) at the poles to 11 miles (18 km) over the equator. Additionally, it has a seasonal variation in height, with summer being its tallest and winter its lowest.

2. Stratosphere

• The second largest layer of air in the atmosphere is called the stratosphere.
• It rises to a height of roughly 50 kilometers (30 miles) above the surface of the earth, just above the tropopause.
• Up to a height of 15 miles (25 km), the air temperature in the stratosphere remains largely constant.
• Then, it gradually grows until it reaches the stratopause.
• The fact that the air temperature in the stratosphere rises with altitude prevents convection and stabilizes the local atmospheric conditions.
• Since there is little water vapor in the stratosphere, ozone is primarily responsible for controlling its temperature regime.
• Ozone concentration rises along with temperature.
• The center of the ozone layer is located at a height of 15–25 km (10–15 miles).
• The stratosphere contains around 90% of the ozone in the atmosphere. The majority of solar UV-B radiation, which has wavelengths between 290 and 320 nm, is absorbed by ozone. These wavelengths can be absorbed by cell nucleic acids, which makes them hazardous to life.

3. Mesosphere

• Temperatures drop in the mesosphere, which is a layer that lies between 50 and 85 kilometers (50 miles) above the surface.
• At the mesopause, the top of this layer, temperatures are the coldest on Earth, especially in the summertime close to the pole.
• Because it had likely been the least investigated of the atmospheric layers, the mesosphere has occasionally been humorously referred to as the “ignorosphere”.
• The intermediate atmosphere, which includes the stratosphere and mesosphere, is occasionally used.

4. Thermosphere

• Above the mesosphere is the thermosphere.
• Depending on solar activity, the thermosphere’s temperature rises with altitude and can range from 600 to 3000 F (600 to 2000 K).
• The minimal quantity of molecular oxygen that is still there is what is causing this rise in temperature.
• The gas molecules are considerably separated at this extremely high altitude.
• The chemical composition of air becomes heavily dependent on altitude over 60 miles (100 km) from the surface of the Earth, and the atmosphere is enriched with lighter gases (atomic oxygen, helium, and hydrogen).
• The Earth’s atmosphere also becomes too thin around 60 miles (100 km) altitude, forcing vehicles to fly at orbital speeds in order to maintain height. The Karman Line is the boundary between aeronautics and astronautics.
• Atomic oxygen becomes the main component of the atmosphere above around 100 miles (160 km) altitude.
• Due to gravitational separation, the remaining gases start to stratify at very high altitudes based on molecular mass.

Exosphere

• The exosphere is the part of the atmosphere that is farthest from the surface of the planet.
• A molecule going upward in the exosphere has a low chance of colliding with another molecule and can either escape to space or be drawn back to Earth by gravity, depending on how quickly it is moving.
• Depending on solar activity, the thermopause or exobase’s lower boundary’s altitude varies from around 150 to 300 miles (250 to 500 km).
• Theoretically, the upper barrier can be identified as the height (about 120,000 miles, or half the distance to the Moon) at which the gravitational pull of the Earth is outweighed by the influence of solar radiation pressure on atomic hydrogen velocities.
• The exosphere, which is visible from space as the geocorona, is thought to reach a distance of at least 60,000 miles from the planet’s surface.
• The exosphere serves as a passageway between the atmosphere of Earth and outer space.

FAQs on Composition and Structure of the Atmosphere

1. What is composition and structure of the atmosphere?

The atmosphere of earth is composed of nitrogen (78%), oxygen (21%), argon (0.9%), carbon dioxide (0.04%) and trace gases.. Together, the two major gases nitrogen and oxygen make up 99% of the atmosphere. The troposphere, stratosphere, mesosphere, ionosphere, and exosphere make up the atmosphere.

2. Why is the composition of the atmosphere important?

The significance of atmospheric composition is the absorption of some sun irradiation and its return to the Earth’s surface so as to increase temperature. The greenhouse effect is what is known as this, and it causes global warming.

3. What is the main function of atmosphere?

The atmosphere protects life on earth by shielding it from incoming ultraviolet (UV) radiation, keeping the planet warm through insulation, and controllingextremes between day and night temperatures. The convection that results from the sun’s heating of the atmosphere’s layers is what drives global air currents and weather patterns.

4. What are the four major components of the atmosphere?

Air is made up of 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.04% carbon dioxide, and other gases in meagre amounts. Air is the term used to describe the complex gas combination that constitutes the Earth’s atmosphere.

5. Which atmosphere is the coldest?

The coldest layer of atmosphere is the mesosphere while the hottest layer of the atmosphere is thermosphere.