Albedo
The fraction of total incident solar electromagnetic radiation reflected back into space by a surface or planetary body.
Governing formula
α = Reflected Solar Irradiance / Total Incident Solar Irradiance
SI unit
Dimensionless Fraction (0.0 to 1.0)
In depth
Earth's average planetary albedo is ~0.30 (30% reflected). Fresh snow and sea ice possess high albedo (~0.80–0.90), reflecting starlight, while dark ocean water has low albedo (~0.06), absorbing solar energy.
Examples in the real world
The ice-albedo positive feedback loop where melting Arctic sea ice lowers surface albedo, increasing ocean heat absorption.