At what altitude does the oxygen level become negligible in the atmosphere?

Correct Option: B. Solution: Oxygen becomes negligible at an altitude of 120 km.

Composition and Structure of Atmosphere

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Summary

Summary of Climate Unit

Key Elements of Atmosphere

Composition and Structure: Atmosphere consists of gases, water vapour, and dust particles.
Elements of Weather and Climate: Temperature, pressure, winds, humidity, clouds, and precipitation.

Layers of the Atmosphere

Troposphere:
- Lowest layer (up to 13 km).
- Contains weather phenomena.
- Temperature decreases with altitude.
Stratosphere:
- Extends up to 50 km.
- Contains ozone layer that absorbs UV radiation.
Mesosphere:
- Extends up to 80 km.
- Temperature decreases with altitude.
Thermosphere:
- Extends up to 400 km.
- Contains ionosphere with charged particles.
Exosphere:
- Outermost layer, merges with outer space.

Important Concepts

Insolation: Angle of incidence and distribution of solar energy.
Heat Budget: Balance of heating and cooling of the atmosphere.
Pressure Belts and Winds: Influence of planetary, seasonal, and local winds.
Precipitation Types: Includes dew, frost, fog, mist, and rainfall.
Climate Classification: Koeppen classification, greenhouse effect, global warming.

Atmospheric Gases

Oxygen: Essential for life, present in significant amounts.
Carbon Dioxide: Important for greenhouse effect, increases due to fossil fuel burning.
Water Vapour: Varies with altitude and affects temperature regulation.
Dust Particles: Includes sea salts, pollen, and smoke; act as nuclei for cloud formation.

Learning Objectives

Understand the composition and structure of the atmosphere.
Identify the main elements of weather and climate.
Explain the significance of the troposphere in atmospheric processes.
Describe the role of water vapor and dust particles in the atmosphere.
Analyze the temperature variations across different layers of the atmosphere.
Discuss the greenhouse effect and the impact of carbon dioxide on climate.
Recognize the importance of the ozone layer in protecting life on Earth.

Detailed Notes

Chapter 7: Composition and Structure of Atmosphere

Introduction

Importance of air for survival
Atmosphere as a mixture of gases

Composition of the Atmosphere

Gases:
- Major gases include oxygen and carbon dioxide.
- Carbon dioxide is transparent to incoming solar radiation but opaque to outgoing terrestrial radiation, contributing to the greenhouse effect.
- Oxygen decreases significantly at heights above 120 km.
Water Vapour:
- Varies with altitude; up to 4% in warm, wet tropics, less than 1% in deserts.
- Acts as a blanket to regulate temperature.
Dust Particles:
- Includes sea salts, fine soil, smoke, and pollen.
- Concentrated in lower layers; can be transported to higher altitudes.

Structure of the Atmosphere

Divided into five layers based on temperature:
1. Troposphere:
  - Lowest layer, average height of 13 km.
  - Contains water vapour and dust; all weather changes occur here.
  - Temperature decreases with altitude.
2. Stratosphere:
  - Extends up to 50 km; contains the ozone layer.
  - Ozone absorbs UV radiation.
3. Mesosphere:
  - Extends up to 80 km; temperature decreases with altitude.
4. Thermosphere:
  - Above the mesosphere; temperature increases with height.
5. Exosphere:
  - Outermost layer; merges with outer space.

Important Features

Tropopause:
- Boundary between troposphere and stratosphere; temperature is nearly constant.
Mesopause:
- Upper limit of the mesosphere.
Ionosphere:
- Contains charged particles; reflects radio waves.

Diagram of the Atmosphere Structure

Figure 7.1: Structure of atmosphere (labelled parts include Troposphere, Stratosphere, Mesosphere, Thermosphere, Exosphere, Tropopause, and Mesopause).

Conclusion

Understanding the atmosphere is crucial for comprehending weather and climate.

Exam Tips & Common Mistakes

Common Mistakes and Exam Tips

Common Pitfalls

Misunderstanding Atmospheric Layers: Students often confuse the characteristics of different atmospheric layers, especially the stratosphere and troposphere. Remember that the troposphere is where weather occurs, while the stratosphere contains the ozone layer.
Ignoring the Role of Water Vapour: Many overlook the significance of water vapour in the atmosphere, which varies with altitude and plays a crucial role in temperature regulation and weather patterns.
Confusing Gas Concentrations: Be careful with the concentrations of gases like carbon dioxide and oxygen at different altitudes. Carbon dioxide is nearly negligible at 120 km, while oxygen decreases significantly as altitude increases.

Exam Tips

Label Diagrams Accurately: When asked to draw the structure of the atmosphere, ensure all layers are correctly labeled, including the tropopause and mesopause.
Focus on Key Elements: In questions about the elements of weather and climate, remember to mention temperature, pressure, winds, humidity, clouds, and precipitation.
Use Multiple Choice Questions for Practice: Familiarize yourself with common multiple-choice questions, such as identifying the major gases in the atmosphere or the characteristics of different atmospheric layers.

Practice & Assessment

Multiple Choice Questions

Troposphere

Stratosphere

Ionosphere

Mesosphere

Correct Answer: C

Solution:

The ionosphere contains electrically charged particles known as ions, which reflect radio waves back to Earth.

Higher humidity at the equator

Stronger convectional currents at the equator

Greater atmospheric pressure at the equator

Higher concentration of dust particles at the equator

Correct Answer: B

Solution:

The thickness of the troposphere is greatest at the equator because heat is transported to great heights by strong convectional currents.

Stratosphere

Mesosphere

Thermosphere

Exosphere

Correct Answer: B

Solution:

In the mesosphere, temperature decreases with the increase in altitude and reaches up to minus 100°C at the height of 80 km.

The intensity of ultraviolet radiation reaching the Earth's surface

The frequency and intensity of weather phenomena

The concentration of ions in the ionosphere

The color of the sky

Correct Answer: B

Solution:

An increase in the thickness of the troposphere would likely affect the frequency and intensity of weather phenomena, as this layer is where most weather occurs.

Nitrogen

Oxygen

Water vapour

Argon

Correct Answer: C

Solution:

Water vapour is a variable gas in the atmosphere, and its concentration decreases with altitude.

Oxygen

Nitrogen

Carbon dioxide

Argon

Correct Answer: C

Solution:

Carbon dioxide is transparent to incoming solar radiation but opaque to outgoing terrestrial radiation, making it a major contributor to the greenhouse effect.

Stratosphere

Troposphere

Mesosphere

Exosphere

Correct Answer: B

Solution:

The troposphere is the lowermost layer of the atmosphere and contains dust particles and water vapour.

50%

75%

99%

100%

Correct Answer: C

Solution:

99% of the total mass of the atmosphere is confined to the height of 32 km from the earth's surface.

90 km

120 km

100 km

150 km

Correct Answer: B

Solution:

Oxygen is almost negligible at the height of 120 km in the atmosphere.

Volcanic eruptions

Burning of fossil fuels

Deforestation

Increased plant respiration

Correct Answer: B

Solution:

The volume of carbon dioxide has been rising mainly due to the burning of fossil fuels.

8 km

13 km

18 km

50 km

Correct Answer: C

Solution:

The troposphere extends roughly to a height of 18 km at the equator.

Reflecting incoming solar radiation

Absorbing terrestrial radiation and contributing to atmospheric stability

Providing energy for photosynthesis

Increasing atmospheric pressure

Correct Answer: B

Solution:

Water vapour absorbs parts of the insolation from the sun and preserves the earth's radiated heat, contributing to atmospheric stability and instability.

Decrease in weather variability

Increase in weather variability

No impact on weather

Complete elimination of weather phenomena

Correct Answer: B

Solution:

An extended troposphere would allow for more convectional currents, potentially increasing the variability and intensity of weather phenomena.

Oxygen

Nitrogen

Carbon dioxide

Helium

Correct Answer: C

Solution:

Carbon dioxide is transparent to incoming solar radiation but opaque to outgoing terrestrial radiation, making it a key component in the greenhouse effect.

Reduction in the greenhouse effect

Increase in global temperatures

Increase in ocean acidity

Increase in atmospheric nitrogen

Correct Answer: A

Solution:

Carbon dioxide is a significant greenhouse gas. Absorbing it would reduce the greenhouse effect, potentially lowering global temperatures.

Decreased solar radiation

Decreased air pressure

Decreased water vapor

Decreased dust particles

Correct Answer: B

Solution:

The primary reason for the decrease in temperature with altitude in the troposphere is the decrease in air pressure.

Troposphere

Stratosphere

Mesosphere

Exosphere

Correct Answer: B

Solution:

The stratosphere contains the ozone layer, which absorbs ultraviolet radiation, causing the temperature to increase with altitude.

Stratosphere

Mesosphere

Troposphere

Thermosphere

Correct Answer: C

Solution:

The troposphere is the lowest layer of the atmosphere where most weather phenomena, such as rain, snow, and storms, occur.

It absorbs terrestrial radiation.

It reflects solar radiation.

It absorbs ultra-violet rays from the sun.

It acts as a greenhouse gas.

Correct Answer: C

Solution:

Ozone absorbs ultra-violet rays radiating from the sun and prevents them from reaching the surface of the earth.

Reflecting radio waves

Absorbing ultraviolet radiation

Maintaining atmospheric pressure

Providing oxygen for breathing

Correct Answer: B

Solution:

The ozone layer in the stratosphere absorbs ultraviolet radiation, protecting life on Earth from harmful UV rays.

Troposphere

Stratosphere

Mesosphere

Thermosphere

Correct Answer: B

Solution:

The stratosphere contains the ozone layer, which absorbs ultraviolet radiation.

Troposphere

Stratosphere

Mesosphere

Ionosphere

Correct Answer: D

Solution:

The ionosphere contains electrically charged particles known as ions.

Troposphere

Stratosphere

Mesosphere

Thermosphere

Correct Answer: B

Solution:

The stratosphere is the atmospheric layer where the temperature increases with altitude. This is due to the presence of the ozone layer, which absorbs ultraviolet radiation from the sun, causing a rise in temperature.

To absorb ultraviolet radiation

To act as hygroscopic nuclei for cloud formation

To increase atmospheric pressure

To reflect solar radiation

Correct Answer: B

Solution:

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

Troposphere

Stratosphere

Mesosphere

Thermosphere

Correct Answer: B

Solution:

The stratosphere contains the ozone layer, which absorbs ultraviolet radiation from the sun.

It contains the ozone layer.

It is the layer where all weather changes occur.

It is the highest layer of the atmosphere.

It reflects radio waves back to Earth.

Correct Answer: B

Solution:

The troposphere is the layer where all weather changes occur, making it crucial for biological activity.

Increase in cloud formation

Decrease in wind speeds

Increase in atmospheric pressure

Decrease in humidity

Correct Answer: A

Solution:

Dust particles act as hygroscopic nuclei, which facilitate cloud formation by providing surfaces for water vapor to condense upon, thus increasing cloud formation.

Decrease in heat retention

Increase in heat retention

No change in heat retention

Fluctuating heat retention

Correct Answer: B

Solution:

Water vapour is a greenhouse gas that absorbs parts of the insolation from the sun and preserves the earth's radiated heat, thus increasing the atmosphere's ability to retain heat.

Stratosphere

Troposphere

Mesosphere

Exosphere

Correct Answer: A

Solution:

In the stratosphere, temperature increases with altitude due to the absorption of ultraviolet radiation by the ozone layer. This is in contrast to the troposphere, where temperature decreases with altitude.

Conduction

Convection

Advection

Greenhouse effect

Correct Answer: D

Solution:

The greenhouse effect is responsible for the heating of the atmosphere by absorbing and re-radiating terrestrial radiation.

They absorb ultraviolet radiation.

They act as hygroscopic nuclei for cloud formation.

They increase atmospheric pressure.

They decrease the temperature of the atmosphere.

Correct Answer: B

Solution:

Dust particles act as hygroscopic nuclei around which water vapour condenses to form clouds.

Troposphere

Stratosphere

Ionosphere

Mesosphere

Correct Answer: C

Solution:

The ionosphere is located between 80 and 400 km above the mesopause and contains electrically charged particles known as ions.

90 km

120 km

100 km

150 km

Correct Answer: B

Solution:

Oxygen is almost in negligible quantity at the height of 120 km.

Troposphere

Stratosphere

Mesosphere

Thermosphere

Correct Answer: C

Solution:

The mesosphere is the layer where the temperature decreases with altitude and can reach up to minus 100°C at the mesopause.

Troposphere

Stratosphere

Mesosphere

Exosphere

Correct Answer: B

Solution:

In the stratosphere, the temperature increases with altitude due to the presence of the ozone layer, which absorbs ultraviolet radiation.

Presence of a dense atmosphere

Presence of electrically charged particles

Presence of significant weather phenomena

Presence of the ozone layer

Correct Answer: B

Solution:

At such altitudes, similar to Earth's ionosphere, the presence of electrically charged particles is expected, which can reflect radio waves.

90 km

120 km

100 km

150 km

Correct Answer: B

Solution:

Oxygen becomes negligible at an altitude of 120 km.

Troposphere

Mesosphere

Stratosphere

Exosphere

Correct Answer: C

Solution:

In the stratosphere, temperature increases with altitude due to the absorption of ultraviolet radiation by the ozone layer.

High humidity

Dry winds

Proximity to oceans

Dense vegetation

Correct Answer: B

Solution:

The higher concentration of dust particles in subtropical and temperate regions is due to dry winds.

Oxygen

Nitrogen

Carbon Dioxide

Argon

Correct Answer: B

Solution:

Nitrogen constitutes about 78% of the atmosphere, making it the primary component by volume.

Enhanced greenhouse effect leading to global warming

Increased oxygen levels in the atmosphere

Reduction in atmospheric pressure

Decrease in water vapour content

Correct Answer: A

Solution:

Carbon dioxide is a greenhouse gas that traps heat in the atmosphere, contributing to the greenhouse effect and global warming. Increased levels of carbon dioxide enhance this effect, leading to a rise in global temperatures.

Increase in ultraviolet radiation reaching the surface

Decrease in surface temperatures

Increase in plant photosynthesis rates

Decrease in skin cancer rates

Correct Answer: D

Solution:

A thicker ozone layer would absorb more ultraviolet radiation, reducing the amount that reaches the Earth's surface, thereby decreasing skin cancer rates.

Ionosphere

Stratosphere

Troposphere

Exosphere

Correct Answer: A

Solution:

The ionosphere is located between 80 and 400 km above the Earth's surface and contains ions, which are electrically charged particles. Temperature in this layer starts increasing with height due to solar radiation.

Increase in ultraviolet radiation reaching the Earth's surface

Decrease in global temperatures

Increase in atmospheric pressure

Reduction in greenhouse gases

Correct Answer: A

Solution:

The ozone layer absorbs harmful ultraviolet (UV) radiation from the sun. If it were depleted, more UV radiation would reach the Earth's surface, leading to increased health risks such as skin cancer and cataracts.

Troposphere

Stratosphere

Ionosphere

Exosphere

Correct Answer: C

Solution:

The ionosphere contains electrically charged particles known as ions, which reflect radio waves.

Increased rainfall and cloud formation

Decreased atmospheric pressure

Reduction in Earth's surface temperature

Increase in oxygen levels

Correct Answer: A

Solution:

Water vapour is a key component in cloud formation and precipitation. Doubling its concentration would likely increase rainfall and cloud formation.

Increase in global temperatures

Decrease in global temperatures

Increase in precipitation

Decrease in atmospheric pressure

Correct Answer: B

Solution:

If the gas is opaque to incoming solar radiation, it would block sunlight from reaching the Earth's surface, leading to a decrease in global temperatures.

Temperature

Pressure

Humidity

Winds

Correct Answer: C

Solution:

Humidity, which involves water vapor in the air, is primarily responsible for the formation of clouds.

Oxygen

Nitrogen

Carbon Dioxide

Argon

Correct Answer: C

Solution:

Carbon dioxide is a major factor in the greenhouse effect as it absorbs and reflects terrestrial radiation.

No change in Earth's energy balance

Increase in Earth's surface temperature

Decrease in atmospheric pressure

Increase in cloud formation

Correct Answer: A

Solution:

If the gas is transparent to both incoming and outgoing radiation, it would not affect Earth's energy balance, resulting in no significant change in temperature.

Increase in surface temperature

Decrease in skin cancer rates

Increase in cloud formation

Decrease in global wind speeds

Correct Answer: B

Solution:

If a new atmospheric layer reflects ultraviolet radiation, it would prevent these harmful rays from reaching the Earth's surface, thereby reducing the incidence of skin cancer caused by UV exposure.

Nitrogen

Oxygen

Carbon dioxide

Argon

Correct Answer: C

Solution:

Carbon dioxide is primarily responsible for the greenhouse effect because it is transparent to incoming solar radiation but opaque to outgoing terrestrial radiation, trapping heat in the atmosphere.

Decrease in global temperatures

Increase in global temperatures

No change in global temperatures

Decrease in atmospheric pressure

Correct Answer: B

Solution:

Carbon dioxide is a greenhouse gas that traps heat in the atmosphere. An increase in its concentration would likely lead to an increase in global temperatures.

Mesosphere

Stratosphere

Ionosphere

Exosphere

Correct Answer: C

Solution:

The ionosphere contains electrically charged particles known as ions, which reflect radio waves back to Earth.

Conduction

Convection

Advection

Absorption by carbon dioxide

Correct Answer: D

Solution:

Carbon dioxide is meteorologically important as it is transparent to incoming solar radiation but opaque to outgoing terrestrial radiation, thus contributing to the greenhouse effect.

Convectional rainfall

Orographic rainfall

Frontal rainfall

Cyclonic rainfall

Correct Answer: D

Solution:

Cyclonic rainfall is most commonly associated with tropical cyclones due to the intense low-pressure systems.

Disruption of vitamin D synthesis in humans

Increase in skin cancer rates

Enhanced photosynthesis in plants

Increase in atmospheric oxygen levels

Correct Answer: A

Solution:

The ozone layer blocks UV radiation, which is necessary for vitamin D synthesis in humans. Blocking all UV radiation could disrupt this process.

Decrease in greenhouse effect and global warming

Increase in greenhouse effect and global warming

No impact on Earth's climate

Increase in atmospheric pressure

Correct Answer: A

Solution:

Methane is a potent greenhouse gas. If a new layer absorbs and neutralizes methane, it would reduce the greenhouse effect, leading to a decrease in global warming.

Troposphere

Stratosphere

Mesosphere

Thermosphere

Correct Answer: B

Solution:

The stratosphere contains the majority of the ozone layer, which is crucial for absorbing harmful ultraviolet radiation from the sun.

Improved long-distance radio communication

Increased interference in radio signals

No impact on radio communication

Decrease in radio signal strength

Correct Answer: A

Solution:

If the properties of the ionosphere, which reflects radio waves, are present at the height of the troposphere, it would enhance the reflection of radio waves, improving long-distance radio communication.

Oxygen

Nitrogen

Helium

Carbon dioxide

Correct Answer: D

Solution:

Carbon dioxide is transparent to incoming solar radiation but opaque to outgoing terrestrial radiation, contributing to the greenhouse effect.

Conduction

Convection

Terrestrial radiation

Advection

Correct Answer: C

Solution:

Terrestrial radiation is the primary process that contributes to the heating of the Earth's atmosphere. It involves the emission of infrared radiation from the Earth's surface, which is absorbed by atmospheric gases, leading to an increase in temperature.

Nitrogen

Oxygen

Argon

Carbon dioxide

Correct Answer: D

Solution:

Carbon dioxide is known to be transparent to incoming solar radiation but opaque to outgoing terrestrial radiation, making it a significant contributor to the greenhouse effect.

Nitrogen

Oxygen

Helium

Carbon dioxide

Correct Answer: C

Solution:

Helium is not a main component of the atmosphere. The major components are nitrogen, oxygen, and carbon dioxide.

True or False

Correct Answer: False

Solution:

The volume of carbon dioxide has been rising in the past few decades mainly because of the burning of fossil fuels.

Correct Answer: True

Solution:

The troposphere is indeed the lowest layer of the atmosphere, and it contains dust particles and water vapour, which are crucial for weather and climate changes.

Correct Answer: False

Solution:

In the troposphere, the temperature decreases with altitude at a rate of 1°C for every 165 meters.

Correct Answer: False

Solution:

The exosphere is the highest layer of the atmosphere, not the lowest.

Correct Answer: True

Solution:

In the troposphere, the temperature decreases with altitude at a rate of approximately 1°C for every 165 meters.

Correct Answer: False

Solution:

In the mesosphere, temperature starts decreasing with the increase in altitude.

Correct Answer: True

Solution:

Water vapour absorbs parts of the sun's insolation and preserves the Earth's radiated heat, acting like a blanket.

Correct Answer: False

Solution:

Most weather changes occur in the troposphere, not the stratosphere. The stratosphere is above the troposphere and contains the ozone layer.

Correct Answer: True

Solution:

In the troposphere, the temperature decreases at the rate of 1°C for every 165m of height.

Correct Answer: True

Solution:

The troposphere is the lowermost layer of the atmosphere and contains dust particles and water vapour. All changes in climate and weather take place in this layer.

Correct Answer: False

Solution:

Water vapour is a variable gas in the atmosphere. Its concentration decreases with altitude and varies with geographical location, being higher in the tropics and lower in polar regions.

Correct Answer: True

Solution:

The atmosphere is indeed composed of gases, water vapour, and dust particles. Its density is highest near the surface of the earth and decreases with increasing altitude.

Correct Answer: True

Solution:

The stratosphere is found above the tropopause and extends up to a height of 50 km. It contains the ozone layer, which absorbs ultraviolet radiation.

Correct Answer: True

Solution:

Carbon dioxide is transparent to incoming solar radiation but opaque to outgoing terrestrial radiation, which makes it a significant contributor to the greenhouse effect.

Correct Answer: True

Solution:

The troposphere is the lowermost layer of the atmosphere and contains dust particles and water vapour. All changes in climate and weather take place in this layer.

Correct Answer: True

Solution:

The atmosphere consists of gases, water vapour, and dust particles, as stated in the excerpts.

Correct Answer: True

Solution:

The stratosphere contains the ozone layer, which absorbs ultraviolet radiation and shields life on Earth from intense, harmful forms of energy.

Correct Answer: False

Solution:

The troposphere is the lowest layer of the atmosphere, not the highest. It extends up to about 18 km at the equator.

Correct Answer: False

Solution:

The exosphere is the highest and least dense layer of the atmosphere, gradually merging with outer space.

Correct Answer: False

Solution:

In the stratosphere, the temperature increases with altitude due to the absorption of ultraviolet radiation by the ozone layer.

Correct Answer: True

Solution:

Ozone is an important component of the atmosphere found between 10 and 50 km above the Earth's surface and acts as a filter by absorbing the ultraviolet rays radiating from the sun.

Correct Answer: True

Solution:

The ozone layer is located in the stratosphere and absorbs ultraviolet radiation, protecting life on Earth.

Correct Answer: True

Solution:

The ionosphere is located between 80 and 400 km above the mesopause and contains electrically charged particles known as ions.

Correct Answer: False

Solution:

The exosphere is the outermost layer of the atmosphere, not the closest to the Earth's surface. The troposphere is the layer closest to the Earth's surface.

Correct Answer: True

Solution:

The ionosphere contains electrically charged particles known as ions, which reflect radio waves transmitted from the Earth back to the surface.

Correct Answer: True

Solution:

Dust particles are concentrated in the lower layers of the atmosphere, but convectional air currents can transport them to great heights.

Correct Answer: True

Solution:

The atmosphere is a mixture of different gases including oxygen, which is essential for humans and animals, and carbon dioxide, which is necessary for plants.

Correct Answer: False

Solution:

Water vapour concentration decreases from the equator towards the poles. It is higher in the warm and wet tropics and lower in the dry and cold polar regions.

Correct Answer: True

Solution:

The troposphere is the lowermost layer of the atmosphere where all changes in climate and weather take place.

Correct Answer: False

Solution:

The troposphere extends up to a height of about 8 km near the poles and about 18 km at the equator, not 50 km.

Correct Answer: True

Solution:

Dust particles serve as hygroscopic nuclei around which water vapour condenses to form clouds.

Correct Answer: False

Solution:

Dust particles are generally concentrated in the lower layers of the atmosphere, although convectional air currents may transport them to great heights.

Correct Answer: True

Solution:

Ozone is located in the stratosphere, between 10 and 50 km above the earth's surface, where it absorbs ultraviolet rays, protecting life on earth.

Correct Answer: True

Solution:

The stratosphere is found above the tropopause and extends up to a height of 50 km. It contains the ozone layer, which absorbs ultraviolet radiation.

Correct Answer: True

Solution:

The ionosphere is located between 80 and 400 km above the mesopause and contains electrically charged particles known as ions.

Correct Answer: True

Solution:

Carbon dioxide is meteorologically important because it is transparent to incoming solar radiation but opaque to outgoing terrestrial radiation, contributing to the greenhouse effect.

Correct Answer: False

Solution:

Water vapour is more abundant in the warm and wet tropics, where it may account for up to four percent of the air by volume, compared to less than one percent in the dry and cold polar regions.

Correct Answer: False

Solution:

In the mesosphere, temperature starts decreasing with the increase in altitude and reaches up to minus 100°C at the height of 80 km.

Correct Answer: False

Solution:

The exosphere is the highest layer of the atmosphere and is very little known due to its extremely rarefied contents.

Composition and Structure of Atmosphere

AI Learning Assistant

Summary

Summary of Climate Unit

Key Elements of Atmosphere

Layers of the Atmosphere

Important Concepts

Atmospheric Gases

Learning Objectives

Learning Objectives

Detailed Notes

Chapter 7: Composition and Structure of Atmosphere

Introduction

Composition of the Atmosphere

Structure of the Atmosphere

Important Features

Diagram of the Atmosphere Structure

Conclusion

Exam Tips & Common Mistakes

Common Mistakes and Exam Tips

Common Pitfalls

Exam Tips

Practice & Assessment

Multiple Choice Questions

Q1.Which atmospheric layer is primarily responsible for reflecting radio waves back to Earth?

Correct Answer: C

Q2.Which factor is primarily responsible for the greater thickness of the troposphere at the equator compared to the poles?

Correct Answer: B

Q3.In which layer of the atmosphere does temperature decrease with altitude and reach up to minus 100°C?

Correct Answer: B

Q4.If the thickness of the troposphere were to increase significantly, which of the following would most likely be affected?

Correct Answer: B

Q5.Which of the following is a variable gas in the atmosphere that decreases with altitude?

Correct Answer: C

Q6.Which of the following gases is primarily responsible for the greenhouse effect due to its ability to absorb and re-radiate terrestrial radiation?

Correct Answer: C

Q7.Which layer of the atmosphere contains the majority of dust particles and water vapour?

Correct Answer: B

Q8.What percentage of the atmosphere's total mass is confined to the height of 32 km from the earth's surface?

Correct Answer: C

Q9.At what height is oxygen almost negligible in the atmosphere?

Correct Answer: B

Q10.What is the primary reason for the increase in atmospheric carbon dioxide in recent decades?

Correct Answer: B

Q11.What is the average height of the troposphere at the equator?

Correct Answer: C

Q12.What is the primary role of water vapour in the atmosphere?

Correct Answer: B

Q13.Imagine a hypothetical scenario where Earth's troposphere extends up to 25 km instead of 13 km. How would this change potentially impact weather phenomena?

Correct Answer: B

Q14.Which of the following gases is primarily responsible for the greenhouse effect due to its ability to absorb terrestrial radiation?

Correct Answer: C

Q15.In a futuristic experiment, scientists manage to create a layer in the atmosphere that can selectively absorb carbon dioxide. What would be the most immediate effect of this on Earth's atmosphere?

Correct Answer: A

Q16.What is the primary reason for the decrease in temperature with altitude in the troposphere?

Correct Answer: B

Q17.In which atmospheric layer does the temperature increase with altitude due to the absorption of ultraviolet radiation?

Correct Answer: B

Q18.In which atmospheric layer do most weather phenomena occur?

Correct Answer: C

Q19.What is the role of ozone in the atmosphere?

Correct Answer: C

Q20.What is the primary role of the ozone layer in the stratosphere?

Correct Answer: B

Q21.Which layer of the atmosphere contains the ozone layer that absorbs ultraviolet radiation?

Correct Answer: B

Q22.Which layer of the atmosphere is known for containing electrically charged particles?

Correct Answer: D

Q23.In which atmospheric layer does the temperature increase with altitude due to the presence of the ozone layer?

Correct Answer: B

Q24.What is the primary role of dust particles in the atmosphere?

Correct Answer: B

Q25.Which layer of the atmosphere contains the ozone layer?

Correct Answer: B

Q26.Why is the troposphere considered the most important layer of the atmosphere for all biological activity?

Correct Answer: B

Q27.During a research study, it was found that the concentration of dust particles in the troposphere increased significantly. What would be the most likely impact of this increase on local weather patterns?

Correct Answer: A

Q28.In a laboratory experiment, scientists create a controlled environment mimicking Earth's atmosphere but with an increased concentration of water vapour. What immediate effect would this have on the atmosphere's ability to retain heat?

Correct Answer: B