Albedo is the fraction of incoming solar radiation that a surface reflects rather than absorbs. It runs from 0, a perfect absorber, to 1, a perfect reflector.
Typical values
| Surface | Approximate albedo |
|---|---|
| Fresh snow | 0.8–0.9 |
| Desert sand | 0.4 |
| Grassland | 0.2–0.25 |
| Earth as a whole | about 0.3 |
| Open ocean | about 0.06 |
| Fresh asphalt | 0.05 |
The Earth reflects roughly 30% of the sunlight that reaches it. Everything else is absorbed and later radiated as heat.
Why it matters
Climate. When bright sea ice melts, it exposes dark ocean that absorbs more heat, which melts more ice. This ice–albedo feedback is one reason the Arctic is warming faster than the global average.
Cities and buildings. Dark roofs and roads absorb heat and add to the urban heat island effect. “Cool roofs” with high-albedo coatings reflect more sunlight and keep buildings cooler in summer.
Solar panels. Bifacial panels collect light on both faces. Over bright ground, such as white gravel or snow, the rear face gets more reflected light and the panel produces more electricity.
Read more: Understanding albedo and its role in cooling our planet.