Which one of the following is associated with ‘Albedo’?

The correct answer is D, Reflecting power. Albedo is the fraction of incident radiation that a surface reflects. It is a number between 0 and 1, often quoted as a percentage. Earth's average planetary albedo is about 0.3, so roughly 30 percent of incoming solar radiation is reflected back to space. Fresh snow has a very high albedo (around 0.8 to 0.9), while the ocean and dark forest have low albedo.

• A (Transmitting power): This is not the term for albedo. The related concept is transmissivity, the fraction of radiation passing through a body.
• B (Absorbing power): This is absorptivity, the fraction absorbed. Albedo and absorptivity are complementary for an opaque surface, so a high albedo means low absorption. A perfect black body has zero albedo.
• C (Emissive power): This is the total energy emitted per unit area per unit time by a body. It follows the Stefan-Boltzmann law, E = σT⁴, and has nothing to do with reflection.

The concept sits in the Earth's radiation budget, which is central to understanding climate. Mains GS-III links it to ice-albedo feedback: melting ice lowers albedo, which increases absorption and accelerates warming.

Trap: Students confuse albedo with absorptivity or emissivity because all three appear in the same radiation chapter. Remember that albedo is always about reflection.