Greenhouse effect basics – UGC NET Question

The natural greenhouse effect arises because gases like water vapour, CO₂ and methane absorb some of the long-wave radiation emitted by the Earth’s surface. They re-radiate energy in all directions, including back towards the surface, raising average temperatures. Without this effect, Earth would be much colder and life as we know it would be impossible. Human activities enhance this natural effect by increasing greenhouse gas concentrations.

Option A:
Option A is correct because it identifies both the trapping of outgoing infrared radiation and the resulting warming of the lower atmosphere and surface.

Option B:
Option B is incorrect since the ozone layer mainly absorbs UV radiation and is a different process from the greenhouse effect, although both occur in the atmosphere.

Option C:
Option C is incorrect; not all incoming solar radiation is reflected—much is absorbed by land, oceans and atmosphere.

Option D:
Option D is incorrect because the term greenhouse effect is used as an analogy for atmospheric warming and is not limited to glass structures for plants.