Question map
Consider the following statements : Statement-I : The atmosphere is heated more by incoming solar radiation than by terrestrial radiation. Statement-II : Carbon dioxide and other greenhouse gases in the atmosphere are good absorbers of long wave radiation. Which one of the following is correct in respect of the above statements ?
Explanation
The correct answer is option D because Statement-I is incorrect while Statement-II is correct.
The bulk of the incoming solar radiation is absorbed by the Earth's surface, not[1] by the atmosphere[2]. The atmosphere transmits the incoming solar radiation but absorbs the vast majority of long wave radiation emitted upwards by the earth's surface[3]. This means the atmosphere is heated MORE by terrestrial (longwave) radiation than by incoming solar radiation, making Statement-I incorrect.
Statement-II is correct because carbon dioxide is transparent to the incoming solar radiation but opaque to the outgoing terrestrial radiation, and it absorbs a part of terrestrial radiation and reflects back some part of it towards the earth's surface[4]. Greenhouse gases in the atmosphere absorb much of the infrared energy emitted from the Earth's surface, preventing it from escaping, and then re-emit this energy in all directions, warming the Earth's surface and lower atmosphere[5].
Therefore, Statement-I is incorrect but Statement-II is correct, making option D the right answer.
Sources- [1] https://www.ipcc.ch/site/assets/uploads/2018/02/ar4-wg1-faqs-1.pdf
- [2] https://www.ipcc.ch/site/assets/uploads/2018/03/ipcc_far_wg_I_full_report.pdf
- [3] FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 11: World Climate and Climate Change > Global Warming > p. 96
- [4] FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 7: Composition and Structure of Atmosphere > Gases > p. 64
- [5] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 17: Climate Change > Role of Greenhouse Gases > p. 255
PROVENANCE & STUDY PATTERN
Full viewThis is a classic 'First Principles' Geography question directly from NCERT Class XI. It tests the fundamental physics of the Greenhouse Effect (Shortwave In vs. Longwave Out). If you understand why temperature decreases with height (Lapse Rate), you know the heat source is the ground, not the sun directly.
This question can be broken into the following sub-statements. Tap a statement sentence to jump into its detailed analysis.
- Statement 1: Is Earth's atmosphere heated more by incoming solar (shortwave) radiation than by terrestrial (longwave) radiation?
- Statement 2: Do carbon dioxide and other greenhouse gases in Earth's atmosphere strongly absorb longwave (thermal infrared) radiation?
- Statement 3: Does absorption of longwave radiation by carbon dioxide and other greenhouse gases explain why Earth's atmosphere is heated more by incoming solar radiation than by terrestrial radiation?
- Provides an energy-budget style breakdown with magnitudes showing atmospheric absorption of solar vs. large longwave exchanges (e.g., back radiation).
- Shows back radiation (~390 W/m2) and surface longwave fluxes are large compared with direct atmospheric solar absorption values in the same budget.
- States that about half of incoming solar is absorbed by the surface rather than directly by the atmosphere.
- Explains that the atmosphere is heated by energy transferred from the surface (thermals, evapotranspiration) and by longwave radiation absorbed by clouds and greenhouse gases.
- Explicitly states that the bulk of incoming solar radiation is absorbed by the Earth's surface, not the atmosphere.
- Implies the atmosphere's heating is largely driven by surface-absorbed solar energy being redistributed rather than direct shortwave absorption by the atmosphere.
States the atmosphere is largely transparent to incoming shortwave solar radiation, with most solar reaching the surface (some near‑IR/water vapour absorption and scattering occur).
A student could combine this with the fact that if most shortwave reaches the surface, then direct atmospheric heating from shortwave is limited compared to surface absorption.
Explains that the warmed Earth radiates longwave energy upward and that this terrestrial longwave is absorbed by greenhouse gases, heating the atmosphere from below.
Combine with estimates of surface emission (from surface temperature) to infer the magnitude of longwave energy available to heat the atmosphere.
Gives the general rule: atmosphere is mostly transparent to incoming shortwave but actively absorbs outgoing terrestrial longwave; links this to temperature lapse rate.
Use this rule plus the vertical distribution of greenhouse gases (concentrated near surface) to argue that absorbed longwave dominates near‑surface atmospheric heating.
Summarises the greenhouse effect: atmosphere transmits incoming solar but absorbs the vast majority of longwave emitted by the surface.
A student could take this qualitative ‘vast majority’ claim and compare it to known solar fluxes (insolation) to judge which flux heats the atmosphere more.
Shows an important exception: high-altitude thermosphere absorbs shortwave solar radiation strongly, producing high temperatures aloft.
Combine this with knowledge of atmospheric mass/energy distribution to note that shortwave heating can dominate in upper layers while longwave heating dominates the lower atmosphere.
- Explicitly says greenhouse gases absorb much of the infrared energy emitted from Earth's surface.
- Notes that these gases re-emit energy in all directions, causing warming of surface and lower atmosphere.
- States the atmosphere absorbs the vast majority of longwave radiation emitted upward by the surface.
- Defines gases that absorb longwave radiation as greenhouse gases, linking absorption to the greenhouse effect.
- Specifically describes carbon dioxide as transparent to incoming solar but opaque to outgoing terrestrial (longwave) radiation.
- Says CO2 absorbs part of terrestrial radiation and reflects some back toward the surface, implicating strong longwave absorption.
- States how energy from the surface is transferred to the atmosphere, explicitly including longwave radiation absorbed by clouds and greenhouse gases.
- Shows that longwave absorption by greenhouse gases is a direct pathway for heating the atmosphere (i.e., atmosphere gains energy from surface-emitted longwave).
- Directly states the atmosphere is relatively transparent to solar but nearly opaque to longwave radiation, linking greenhouse gases to strong longwave absorption.
- Adds that the atmosphere typically absorbs most longwave radiation emitted by the surface, implying significant atmospheric heating from terrestrial (longwave) radiation.
- Provides quantitative energy-flow figures showing how much solar is incident and how much is absorbed by the atmosphere, allowing comparison between direct solar absorption and longwave exchanges.
- Includes large values for surface and back radiation, illustrating the substantial longwave fluxes exchanged between surface and atmosphere.
States that the Earth radiates longwave energy which is absorbed by CO2 and other greenhouse gases, meaning the atmosphere is heated indirectly from terrestrial radiation.
A student could combine this with the basic fact that most solar energy reaches and heats the surface (shortwave passes through) to compare the relative roles of incoming solar vs. outgoing terrestrial heating of the atmosphere.
Explains the general rule that the atmosphere is largely transparent to shortwave solar radiation but absorbs most longwave radiation emitted by the surface (the greenhouse effect).
Use a world-map or energy-balance numbers to estimate how much energy arrives as shortwave at the surface vs. how much is re-emitted as longwave and then absorbed to judge which process supplies more atmospheric heating.
Gives an explicit example: CO2 is transparent to incoming solar but opaque to outgoing terrestrial radiation and reflects some back to the surface — highlighting the differing interaction with shortwave vs. longwave.
A student could apply this pattern to infer vertical heating profiles (surface-heated then atmosphere heated by upwelling longwave) and compare that with direct solar heating of atmospheric layers.
Describes the mechanism that radiatively active gases absorb outgoing longwave, re-emit it (some downward), and thus keep the lower troposphere warmed.
Combine this process description with basic quantitative solar flux values (solar constant, surface absorption) to assess whether the absorbed/re-emitted longwave can account for greater atmospheric heating than direct solar absorption.
Links the atmospheric lapse rate (temperature decrease with altitude) to the pattern that the atmosphere is transparent to incoming shortwave but actively absorbs outgoing longwave; greenhouse gases concentration near the surface affects heating.
Use the lapse-rate implication and knowledge of greenhouse gas vertical distribution to reason whether atmospheric heating is dominated by surface-emitted longwave absorption versus direct solar heating aloft.
- [THE VERDICT]: Sitter. Directly solvable from NCERT Class XI (Fundamentals of Physical Geography), Chapter 8: Solar Radiation, Heat Balance and Temperature.
- [THE CONCEPTUAL TRIGGER]: The 'Heat Budget' of the Earth. Specifically, the distinction between 'Insolation' (Shortwave) and 'Terrestrial Radiation' (Longwave).
- [THE HORIZONTAL EXPANSION]: Memorize the Heat Budget breakdown: 35 units reflected (Albedo), 14 units absorbed by atmosphere (Solar), 51 units absorbed by Earth. Key Albedo sequence: Fresh Snow (80-90%) > Clouds > Sand > Forest > Ocean. Understand 'Normal Lapse Rate' (6.5°C/km) vs 'Adiabatic Lapse Rate'.
- [THE STRATEGIC METACOGNITION]: Do not just memorize 'CO2 causes warming'. Ask 'How?'. The mechanism (transparency to shortwave, opacity to longwave) is the core examinable fact. Always link physical phenomena (Lapse Rate) to their cause (Ground-based heating).
Greenhouse gases absorb outgoing longwave infrared from the warmed surface, producing most atmospheric heating rather than direct shortwave absorption.
High-yield for questions on climate, radiative forcing and global warming; links radiative transfer to surface–atmosphere coupling and policy debates on greenhouse gas emissions. Mastery enables explanation of atmospheric warming mechanisms, temperature profiles, and impacts of CO2 and water vapour changes.
- FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 11: World Climate and Climate Change > Global Warming > p. 96
- FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 8: Solar Radiation, Heat Balance and Temperature > Terrestrial Radiation > p. 69
- Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 22: Vertical Distribution of Temperature > 22.2. Lapse Rate > p. 295
The atmosphere is largely transparent to solar shortwave, so most solar energy reaches and heats the surface rather than directly heating the air.
Essential for understanding surface heating, diurnal temperature range, and the role of clouds/albedo; helps answer questions contrasting surface vs atmospheric energy uptake and interpreting observational radiation budgets.
- FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 8: Solar Radiation, Heat Balance and Temperature > The Passage of Solar Radiation through the Atmosphere > p. 68
- FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 8: Solar Radiation, Heat Balance and Temperature > SOLAR RADIATION > p. 67
- Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 14: Climate > lnsolation > p. 131
Earth maintains energy balance by receiving shortwave insolation and returning energy as longwave terrestrial radiation, which is central to how heat is distributed between surface and atmosphere.
Core concept for physical geography and climate sections; useful for solving energy-balance problems, explaining feedbacks (clouds, albedo), and framing questions on temperature equilibrium and climate change.
- Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 21: Horizontal Distribution of Temperature > 21.5. Heat Budget > p. 293
- Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 17: Climate Change > Emission > p. 255
Greenhouse gases are defined by their ability to absorb outgoing longwave (thermal infrared) radiation and thereby trap heat.
High-yield for questions on radiative forcing and climate: it links atmospheric composition to surface warming and helps explain why changes in gas concentrations alter Earth’s energy balance. Mastering this aids answers on greenhouse effect mechanics, climate drivers, and mitigation rationale.
- Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 17: Climate Change > Role of Greenhouse Gases > p. 255
- FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 11: World Climate and Climate Change > Global Warming > p. 96
Carbon dioxide transmits incoming solar shortwave radiation but absorbs and re-emits outgoing terrestrial longwave radiation.
Crucial for explaining CO2’s specific role in warming, trends in atmospheric CO2, and policy debates about fossil fuel emissions; connects to topics on radiative properties, energy balance, and anthropogenic climate change questions.
- FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 7: Composition and Structure of Atmosphere > Gases > p. 64
- Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 7: Climate Change > 2. greenhouse gases > p. 9
Absorbed longwave radiation is re-emitted by gases in all directions, including back toward the surface, warming the lower atmosphere.
Useful for explaining temperature profiles, the mechanism of the greenhouse effect, and the distinction between solar heating and terrestrial re-radiation; equips aspirants to answer process-based questions on climate dynamics and feedbacks.
- Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 17: Climate Change > Role of Greenhouse Gases > p. 255
- Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 6: Environmental Degradation and Management > Greenhouse Effect and Global Warming > p. 7
The atmosphere is largely transparent to incoming shortwave solar radiation but absorbs outgoing longwave terrestrial radiation, which controls how the atmosphere is warmed.
High-yield for UPSC because it is central to questions on Earth's energy balance, climate change and the greenhouse mechanism. Links physical geography to environmental science and policy topics (radiative balance, global warming). Enables tackling questions on why surface and lower atmosphere temperatures differ from a no-atmosphere case and on effects of changing greenhouse gas concentrations.
- FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 11: World Climate and Climate Change > Global Warming > p. 96
- FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 8: Solar Radiation, Heat Balance and Temperature > The Passage of Solar Radiation through the Atmosphere > p. 68
The 'Atmospheric Window' (8–14 µm). While CO2 absorbs longwave, there is a specific spectral window where the atmosphere is transparent to outgoing terrestrial radiation, allowing heat to escape. Clouds close this window, which is why cloudy nights are warmer.
Use the 'Mountain Top Logic'. If the atmosphere were heated primarily by incoming solar radiation (from above), the upper layers (mountains) would be warmer than the plains. Since mountains are colder, the heat source must be from *below* (the ground/terrestrial radiation). Thus, Statement I is physically impossible given the existence of the Lapse Rate.
Link this to Environment (Climate Change): The concept of 'Global Warming Potential' (GWP) is based on this radiative efficiency. CO2 is the baseline (GWP=1). Methane absorbs longwave 25-30x more effectively. SF6 is ~23,500x. This physics dictates the Kyoto/Paris baskets.