Radiative Cooling
Everything above absolute zero glows — mostly at infrared wavelengths we can't see. Radiative cooling is the heat that leaves an object as this glow. When a surface can emit through the atmospheric window, some of that heat is lost directly to space.
Scientific detail
Radiative cooling flux is described by the Stefan–Boltzmann law integrated over the emissive spectrum: q_rad = ε σ (T_s⁴ − T_sky⁴). In the 8–13 μm atmospheric window, sky brightness temperature can be 40–60 K below ambient under clear conditions, enabling net radiative heat loss even in warm climates. Cloud cover, water vapour and aerosols raise T_sky and diminish the effect.
Related terms
Passive Daytime Radiative Cooling
A material that stays cooler than the air even under direct sunlight by radiating heat to the cold sky.
Atmospheric Window
A range of infrared wavelengths (roughly 8–13 μm) where the atmosphere absorbs relatively little of Earth's outgoing thermal radiation.
Thermal Emittance
How efficiently a surface releases heat as infrared radiation.
Surface Energy Balance
The bookkeeping of energy flowing into and out of a surface at every moment.
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Passive Cooling
Everything MEER publishes on passive cooling — reflective roofs, PDRC materials, canopies, reservoir systems, projects, publications and stories, gathered in one place.
Radiative Cooling & PDRC
PDRC materials, the atmospheric window, thermal emittance and the practical engineering of surfaces that radiate heat directly to deep space.