Which one of the following reflects back more sunlight as compared to other three ?

Question

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Correct — C, Land covered with fresh snow. The share of incoming sunlight a surface reflects is its albedo. Fresh, clean snow has the highest albedo of any common land surface — about 0.80 to 0.90 (80 to 90 percent). Sand deserts (about 0.25 to 0.40), paddy / crop land (about 0.15 to 0.25) and prairie / grassland (about 0.20) reflect far less and absorb the rest. So land under fresh snow reflects back the most sunlight.

Why the other options are wrong — (a) Bright to the eye, but a sand desert's albedo is only about 0.25 to 0.40 — well below fresh snow; it absorbs most of the sunlight that strikes it (hence very hot days).  (b) A vegetated, often wet surface with low albedo (about 0.15 to 0.25); green leaves absorb most incoming light for photosynthesis and heating.  (d) Grassland / prairie has an albedo around 0.20 — it reflects only a small fraction of sunlight compared with the roughly 0.85 of fresh snow.

Concept: Albedo is the fraction of incident solar radiation a surface reflects (0 = perfect absorber, 1 = perfect reflector). Light, white, dry surfaces have high albedo; dark, wet, vegetated surfaces have low albedo. Fresh snow sits at the very top of the scale; as snow ages and gets dirty its albedo falls. Albedo drives the ice-albedo feedback: when snow or ice melts it exposes darker ground or water that absorbs more heat, which accelerates further warming.

State PCS 2021 Q13 — Geography PYQ with Answer

State PCS 2021 Q13 — Geography PYQ with Answer