Assertion A: Earth's atmosphere keeps the planet warm mainly by reflecting the incoming solar radiation.
Reason R: Greenhouse gases absorb longwave radiation emitted from the earth's surface.
In the light of the above statements, choose the most appropriate answer from the options given below
Assertion A Analysis: Atmospheric Warming Mechanism
Assertion A states that Earth's atmosphere keeps the planet warm mainly by reflecting incoming solar radiation. This is incorrect. Reflection of solar radiation (albedo) actually contributes to cooling the planet by sending energy back to space. The primary mechanism for atmospheric warming is the trapping of heat, not reflection of incoming sunlight.
Reason R Analysis: Greenhouse Gas Role
Reason R correctly explains that greenhouse gases absorb longwave radiation emitted from the Earth's surface. After the Earth absorbs solar energy, it radiates heat back towards space as infrared (longwave) radiation. Greenhouse gases, such as carbon dioxide ($CO_2$) and water vapor ($H_2O$), effectively absorb this outgoing radiation. They then re-radiate it in all directions, including back towards the surface, which warms the lower atmosphere and the planet's surface. This process is known as the greenhouse effect.
Conclusion on Statements
Based on the analysis:
- Assertion A is incorrect because atmospheric warming is primarily due to heat trapping, not the reflection of incoming solar radiation.
- Reason R is correct as greenhouse gases play a crucial role in absorbing and re-emitting the Earth's outgoing longwave radiation.
Therefore, Assertion A is not correct, but Reason R is correct.
Important Questions from Atmosphere
- What is atmospheric window?
- Which one of the following gas was not released through volcanoes around 4 billion years ago?
Absolute humidity in atmosphere at $ 10^\circ $ is $5.0$ g/m$^3$ and maximum amount of water air can hold at same temperature is $ 10$ g m$^3$. What will be the relative humidity at the same temperature?
- The change of atmospheric air temperature with altitude is _____
- Assertion (A) : Warmth of sun’s rays is advantageous during evening time.
Reason (R) : Evening air contains moisture which absorbs the heat and allows the light.
Select the most appropriate option :
