Albedo
The fraction of solar radiation reflected by a surface back to space, affecting Earth's energy balance.
Formula
Albedo (α) = reflected radiation ÷ incoming radiation
Real World
As Arctic sea ice melts, dark ocean water (albedo ~0.06) replaces reflective ice (albedo ~0.9), absorbing far more solar energy and accelerating further warming — a process NASA satellites have tracked accelerating since the 1990s.
Exam Focus
Always link albedo change to the ice-albedo positive feedback loop — examiners expect the feedback mechanism, not just the definition.
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