Define albedo and identify its role in Earth’s energy balance.

Define albedo and identify its role in Earth’s energy balance.

• A. The speed at which light travels through a surface.
• B. The amount of sunlight absorbed by a surface.
• C. The fraction of sunlight reflected by a surface.
• D. The temperature of a surface.

Answer: (C)

Albedo is a measure of how much sunlight a surface reflects. It represents the fraction of incoming solar radiation that is bounced back into space, not absorbed. This matters for Earth’s energy balance because it helps determine how much solar energy stays in the planet system as heat. Surfaces with high albedo, like fresh snow or ice, reflect most of the sunlight and stay cooler because less energy is absorbed. Surfaces with low albedo, like oceans or forests, absorb most of the sunlight, warming the surface. Albedo can change with seasons, angle of sunlight, and surface conditions, and because it affects absorption, it can create feedbacks (for example, melting ice lowers albedo, leading to more absorption and further warming). The other options describe speed of light through a surface, the amount absorbed, or temperature, which are not what albedo measures.

Albedo is a measure of how much sunlight a surface reflects. It represents the fraction of incoming solar radiation that is bounced back into space, not absorbed. This matters for Earth’s energy balance because it helps determine how much solar energy stays in the planet system as heat. Surfaces with high albedo, like fresh snow or ice, reflect most of the sunlight and stay cooler because less energy is absorbed. Surfaces with low albedo, like oceans or forests, absorb most of the sunlight, warming the surface. Albedo can change with seasons, angle of sunlight, and surface conditions, and because it affects absorption, it can create feedbacks (for example, melting ice lowers albedo, leading to more absorption and further warming). The other options describe speed of light through a surface, the amount absorbed, or temperature, which are not what albedo measures.