Consider the following statements:
I. Without the atmosphere, temperature would be well below freezing point everywhere on the
Earth's surface.
II. Heat absorbed and trapped by the atmosphere maintains our planet's average temperature.
III. Atmosphere's gases, like carbon dioxide, are particularly good at absorbing and trapping radiation.
Which of the statements given above are correct?

Correct Answer:

(c) I, II and III

Explanation of the Correct Answer:

All three statements are correct and interrelated aspects of how the Earth's atmosphere regulates temperature:

Statement I: Without the atmosphere, temperature would be well below freezing point everywhere on the Earth's surface.

• Correct.
• The average surface temperature of Earth is about 15°C due to the greenhouse effect.
• Without an atmosphere, Earth’s average temperature would fall to around 18°C, making life as we know it impossible.
• The atmosphere traps heat and slows down the rate of heat loss to outer space.

Statement II: Heat absorbed and trapped by the atmosphere maintains our planet's average temperature.

• Correct.
• The greenhouse effect allows solar radiation to enter, but certain gases (like CO₂ and water vapor) trap the infrared radiation (heat) re-emitted by Earth’s surface.
• This process stabilizes Earth’s climate and keeps it habitable.

Statement III: Atmosphere's gases, like carbon dioxide, are particularly good at absorbing and trapping radiation.

• Correct.
• Greenhouse gases such as carbon dioxide (CO₂), methane (CH₄), and water vapor (H₂O) absorb outgoing infrared radiation.
• CO₂, in particular, is efficient at trapping longwave radiation, significantly contributing to warming.

Why Other Options Are Incorrect:

• (a) I and III only: Excludes II, which is essential and correct.
• (b) I and II only: Excludes III, which is scientifically validated.
• (d) II and III only: Excludes I, which is fundamental to understanding the role of the atmosphere.

Relevant Supplementary Information

Table: Greenhouse Gases and Their Roles

Table: Comparison – Earth with vs. without Atmosphere

Related Concepts:

• Greenhouse Effect: Natural process by which certain gases trap heat in Earth's atmosphere.
• Infrared Radiation: Longwave radiation emitted by Earth after absorbing sunlight.
• Earth's Energy Budget: Balance between incoming solar energy and outgoing infrared radiation.

Current Relevance:

• Understanding the natural greenhouse effect is essential for analyzing climate change.
• Rising levels of CO₂ and CH₄ due to human activity are intensifying the greenhouse effect, leading to global warming.
• International efforts like the Paris Agreement focus on reducing greenhouse gas emissions.

Table 1: Role of the Atmosphere in Earth's Temperature Regulation

Table 2: Greenhouse Effect – Natural vs. Enhanced

Table 3: Key Greenhouse Gases and Their Characteristics

Table 4: Heat Transfer and Atmospheric Interaction

Table 5: Statement-Based Concept Mapping

Extension: Atmospheric Composition (By Volume)