Test: Composition & Structure Of Atmosphere - 2 - Humanities/Arts MCQ

The ozone layer is primarily found in the Stratosphere. This layer of the Earth's atmosphere contains a high concentration of ozone (O₃) molecules, which play a crucial role in absorbing and scattering the solar ultraviolet radiation, protecting living organisms from harmful UV rays.

The chief elements of the atmosphere include various physical factors that characterize its state and behavior. These elements include wind, temperature, and pressure, among others. Each of these factors plays a critical role in defining the meteorological conditions of the atmosphere.
Wind, temperature, and pressure are fundamental atmospheric elements that interact to influence weather patterns, climate conditions, and the general environment of the Earth.

Carbon Dioxide:

• Carbon dioxide is meteorologically a very important gas.
• It is transparent to the incoming solar radiation but opaque to the outgoing terrestrial radiation.
• It absorbs a part of terrestrial radiation and reflects back some part of it towards the earth’s surface.
• It is largely responsible for the greenhouse effect.
• The volume of other gases is constant but the volume of carbon dioxide has been rising in the past few decades mainly because of the burning of fossil fuels.
• This has also increased the temperature of the air.

​Thus, carbon dioxide is transparent to incoming solar radiation and opaque to outgoing terrestrial radiation.

• Atmosphere: The earth is surrounded by a layer of gas called the atmosphere. This thin blanket of air is an integral and important aspect of the planet.
• Gaseous composition of the atmosphere:
  • The air in the atmosphere is a mixture of many gases like nitrogen, oxygen, carbon dioxide, and water vapours.
  • The atmosphere is composed mainly of nitrogen and oxygen
  • Nitrogen and oxygen are two gases that make up the bulk of the atmosphere.
  • Carbon dioxide, helium, ozone, argon, and hydrogen are found in lesser quantities.
  • Nitrogen is the most plentiful gas in the air. It comprises 78% of the total composition of air.
  • Oxygen holding the second position by volume constitutes 21% of the atmosphere.

The atmosphere plays a crucial role in sustaining and protecting life on Earth through several mechanisms:

• The ozone layer (A) absorbs and scatters the majority of the sun's harmful ultraviolet radiation, protecting living organisms from DNA damage and other harmful effects.
• Greenhouse gases (B) like carbon dioxide and methane trap heat in the atmosphere, creating a warmer environment that is suitable for life as we know it. This greenhouse effect increases the average temperature near the Earth's surface, making it habitable.
• Oxygen (C), a major component of the atmosphere, is essential for the respiration of most living organisms and supports the combustion processes that are critical for various human activities.

Answer: D: all of the choices

Each of these aspects contributes significantly to creating and maintaining conditions that support diverse life forms on our planet.

The mesosphere is one of the layers of Earth's atmosphere and is situated above the stratosphere. It extends from about 50 kilometers (31 miles) to 85 kilometers (53 miles) above the Earth's surface. The layer above the mesosphere is the thermosphere.
This positioning makes the mesosphere the third layer of the atmosphere, directly above the stratosphere and below the thermosphere.

The layer of the atmosphere most useful for various biological activities is the troposphere. This is the lowest layer of Earth's atmosphere and extends from the Earth's surface up to about 10 kilometers (6 miles) in altitude. The troposphere contains approximately 75% of the atmosphere's mass and is where almost all weather conditions take place. It is rich in oxygen and nitrogen which are essential for life, and the temperature and pressure conditions are suitable for biological activities.

Dust particles include sea salt, pollen, ash, smoke soot, and fine soil, which play a role in cloud formation.

Oxygen is present in very negligible amounts at a height of 120 km from the Earth's surface.

The air is an integral part of the earth’s mass and 99 per cent of the total mass of the atmosphere is confined to the height of 32 km from the earth’s surface.

Water vapour is a variable gas that:

• Decreases as altitude increases.
• Can make up to 4% of the air in warm, humid areas.
• May drop to less than 1% in cold, dry regions.
• Also decreases from the equator towards the poles.

It plays a crucial role by:

• Absorbing solar energy.
• Preserving the Earth's heat, acting like a blanket.
• Influencing air stability and instability.

Dust and salt particles act as hygroscopic nuclei around which water vapour condenses to produce clouds.

• The troposphere is the lowest layer of the atmosphere.
• Temperature drops by 1°C for every 165m of altitude.
• This layer is crucial for weather and climate changes.
• It contains dust and water vapour, which are essential for cloud formation.
• Convection currents transport heat, especially at the equator.

The boundary between the troposphere and the stratosphere is called the tropopause, where temperatures stabilise.

The zone separating the troposphere from the stratosphere is known as the tropopause.

The tropopause serves as a boundary between two significant layers of the atmosphere:

• The troposphere is the lowest layer, where weather events occur and temperature decreases with altitude.
• The stratosphere lies above the tropopause, extending up to 50 km, and contains the ozone layer, which protects life on Earth from harmful ultraviolet radiation.

At the tropopause, the air temperature is approximately:

• -80°C over the equator
• -45°C over the poles

This layer is crucial for maintaining the stability of the atmosphere and plays a vital role in climatic conditions.

The temperature starts increasing with height in the thermosphere.

The thermosphere is the layer of the atmosphere where temperature rises as altitude increases. Key points include:

• The thermosphere extends from about 80 km to 400 km above the Earth's surface.
• It contains electrically charged particles, known as ions, which are crucial for radio wave transmission.
• Temperature can reach up to 2,500 °C or higher due to solar radiation absorption.
• This layer plays a significant role in the ionosphere, which reflects radio waves back to Earth.

In contrast, the layers below the thermosphere, such as the troposphere and stratosphere, exhibit a decrease in temperature with altitude.