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Greenhouse effect
Beginner
Atmospheric gases trap outgoing heat radiation.
Atmospheric gases (CO₂, CH₄, H₂O) transmit visible sunlight but absorb outgoing infrared, warming Earth from −18 °C to +15 °C. Increased concentrations strengthen it.
Venus's thick CO₂ atmosphere gives 460 °C.
The natural effect is essential for life.
In more detail
The greenhouse effect occurs when gases such as carbon dioxide and water vapour absorb infrared radiation from Earth's surface and re-emit it, keeping the planet warmer than it would be otherwise.
Real-world uses
- Climate models use radiative transfer to predict warming.
- Greenhouses trap heat by a related but different mechanism.
- Climate scientists use the greenhouse effect to explain why the Earth's surface is warmer than it would be without an atmosphere.
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Frequently asked questions
Is the greenhouse effect bad?
Without it Earth would be far colder, but enhanced warming from human emissions is a problem.
Does a greenhouse work like this gas effect?
Greenhouses mainly stop air movement, while the atmospheric effect is radiative.
Does the greenhouse effect only harm the planet?
No. Without it, the Earth's average temperature would be far below freezing, so it is essential for life.
Related topics in Heat & Thermodynamics
Heat death of the universe · Arrow of time · Humidity and dew point · Thermal equilibrium in the Sun-Earth system · Thermal conductivity of materials · Insulation and R-value