Correct Option
The correct option is 2 and 3 only.
Explanation
Carbon dioxide is a meteorologically significant gas constituting approximately 0.036% of the Earth's atmosphere. Its physical properties regarding radiation transmission are fundamental to the greenhouse effect and the Earth's heat balance.
Statement-wise Analysis
- Statement 1 is Incorrect. Carbon dioxide is transparent to incoming solar radiation. Solar radiation primarily consists of short wavelengths, which pass through carbon dioxide molecules without significant absorption, allowing them to reach the Earth's surface.
- Statement 2 is Correct. Carbon dioxide is opaque to outgoing terrestrial radiation. The Earth radiates heat back into space in the form of longwave radiation. Carbon dioxide absorbs a portion of this terrestrial radiation and reflects some of it back towards the Earth’s surface, thereby maintaining the planet's temperature.
- Statement 3 is Correct. While the density of the atmosphere decreases rapidly with height, the composition varies. Carbon dioxide and water vapour are generally found only up to a height of 90 km from the surface of the Earth. In contrast, oxygen is found in significant quantities up to 120 km.
Key Takeaway
Carbon Dioxide acts as a greenhouse gas because it is transparent to incoming shortwave solar radiation but opaque to outgoing longwave terrestrial radiation, and it is confined to the lower 90 km of the atmosphere.