Albedo
Albedo is a number between 0 and 1 that tells you how reflective a surface is. Fresh snow is around 0.85; dark asphalt is closer to 0.05. Raising albedo across a city dramatically reduces how much solar heat it absorbs.
Scientific detail
Broadband surface albedo (α) is the spectrally weighted ratio of reflected to incident shortwave irradiance across ~0.3–2.5 μm. In the Earth's energy balance, a Δα of +0.01 applied globally corresponds to roughly −1.4 W m⁻² of effective radiative forcing — a lever comparable in magnitude to major greenhouse-gas concentrations. Local albedo increases reduce absorbed insolation directly and can, at scale, produce measurable regional cooling.
Related terms
Solar Reflectance
The fraction of incoming solar energy a surface reflects across the sun's spectrum.
Reflective Cooling
Cooling by bouncing sunlight away from a surface before it can be absorbed as heat.
Surface Energy Balance
The bookkeeping of energy flowing into and out of a surface at every moment.
Passive Daytime Radiative Cooling
A material that stays cooler than the air even under direct sunlight by radiating heat to the cold sky.
Where this concept shows up on MEER
Related projects
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Explore in topic hubs
Curated collections of MEER research, projects, publications and stories that feature this term.
Passive Cooling
Everything MEER publishes on passive cooling — reflective roofs, PDRC materials, canopies, reservoir systems, projects, publications and stories, gathered in one place.
Urban Heat
The urban heat-island effect, its measurement, and how MEER's reflective roofs, canopies and pavements reduce peak city temperatures and protect vulnerable urban populations.
Albedo & Reflectivity
Understanding planetary albedo, surface reflectivity, ice-albedo feedback, and why restoring Earth's reflectivity matters for global temperature.
Climate Science
MEER's collected explainers on climate science — energy balance, the greenhouse effect, radiative forcing, tipping points and planetary boundaries.
Water & Cooling
How passive cooling and reflective materials protect water resources: reservoir systems, evaporation reduction, and the hydrological co-benefits of surface cooling.
Agriculture & Cooling
How reflective materials, canopies and passive cooling protect agricultural yields, livestock and rural livelihoods under extreme heat.
Climate Adaptation
MEER's approach to climate adaptation: adaptive mitigation, radiative forcing, resilience, and the policy context around passive surface cooling.