BharatNotes Albedo
noun (plural: albedos or albedoes)Usage in a UPSC answer
The retreat of Arctic sea ice lowers the planet's albedo, setting off a dangerous feedback loop in which darker ocean waters absorb more solar radiation and further accelerate global warming — a phenomenon that lends urgency to India's advocacy of climate justice at multilateral forums.
Synonyms
Antonyms
Word Family
albedo (n), albedos (n pl), alb (n), albumen (n), albino (n), albescent (adj)
Root
Latin albus = white + -ēdō = abstract noun suffix → albēdō = whiteness
Etymology
From Latin albēdō ("whiteness"), from albus ("white") + -ēdō (abstract noun suffix); first used in English in an astronomical context in 1859.
Memory Hook
Think ALBino — Latin albus means 'white'. ALBEDO measures how 'white' (reflective) a surface is: albino-white snow has high albedo and bounces sunlight back; dark asphalt has low albedo and soaks it up.
How This Word Works in UPSC Writing
The fraction of incoming solar radiation that a surface reflects. Fresh snow reflects most of what falls on it while dark ocean and dense forest reflect very little, and the Earth's average sits near 0.30. The concept earns its weight through the ice-albedo feedback, the clearest positive feedback in the climate system: warming melts ice, the darker ocean or land exposed beneath absorbs more radiation, and that additional absorption drives further warming and further melting. This is a principal reason the polar regions warm faster than the global average. The same physics operates locally, since the urban heat island is partly an albedo effect, dark asphalt and roofing absorbing far more than vegetation or pale surfaces, which is the reasoning behind cool-roof programmes. Aerosols and clouds complicate the picture by raising albedo and exerting a cooling influence, so polluted skies can mask part of the warming greenhouse gases would otherwise produce.
Don’t Confuse It With
Albedo is a ratio between zero and one, the proportion of shortwave radiation reflected, rather than a quantity of energy. Insolation is the energy arriving and absorption the complementary fraction retained, since albedo and absorptivity together account for all of it. Emissivity describes how efficiently a surface radiates longwave energy outward, which is a distinct property from reflecting shortwave. A positive feedback amplifies an initial change, as the ice-albedo mechanism does, while a negative feedback damps it down.
Hindi Meaning
एल्बिडो or परावर्तनांक (parāvartanānk).
Common Questions
- What is the ice-albedo feedback?
- Warming melts reflective ice, exposing darker ocean or land that absorbs more solar radiation, which causes further warming and further melting in a self-reinforcing loop.
- Why do the polar regions warm faster than the global average?
- Largely because of the ice-albedo feedback, as retreating ice and snow expose darker surfaces that absorb far more of the incoming radiation than the ice they replaced.
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