Which surface absorbs more solar radiation?

Which surface absorbs more solar radiation?

• A. White cement
• B. Beige sand
• C. Brown mulch
• D. Yellow pebbles

Answer: (C)

Absorption of solar radiation is driven mainly by color and surface reflectivity. Darker colors have lower reflectivity (albedo) and soak up more sunlight as heat, while lighter colors reflect much of the light. Brown mulch is dark, so it absorbs a larger portion of the sun’s energy and heats up more than the lighter surfaces. White cement reflects most sunlight, so its absorption is low. Beige sand is lighter and absorbs less than brown mulch but more than white cement, and yellow pebbles are relatively bright, so they also reflect a good portion of sunlight. The result is that brown mulch tends to take in more solar energy overall.

Absorption of solar radiation is driven mainly by color and surface reflectivity. Darker colors have lower reflectivity (albedo) and soak up more sunlight as heat, while lighter colors reflect much of the light. Brown mulch is dark, so it absorbs a larger portion of the sun’s energy and heats up more than the lighter surfaces. White cement reflects most sunlight, so its absorption is low. Beige sand is lighter and absorbs less than brown mulch but more than white cement, and yellow pebbles are relatively bright, so they also reflect a good portion of sunlight. The result is that brown mulch tends to take in more solar energy overall.