NASA CERES map of net radiation averaged over 2000–2015, with a −200 to +200 W m⁻² colour scale.

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Preparing the 3D view

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Model scale

One-layer radiation experiment. arrows show global mean fluxes.

Sunlight absorbed 238.2 · Surface emits 390.5 · Back radiation 152.3 W/m².

How to read these results

Surface equilibrium 14.9 °C · top-of-atmosphere balance 0.0 W/m². Follow the wave symbols to trace the exchange of energy.

Earth’s energy budget

Trace energy entering and leaving Earth, and explain how reflection and atmospheric absorption affect the surface temperature.

Drag to rotate. Hold Ctrl and scroll to zoom, or pinch on a touch screen.

Why it happens

Earth reflects some incoming sunlight and absorbs the rest. Its temperature adjusts as outgoing thermal radiation balances absorbed energy; greenhouse gases change the exchange of thermal radiation.

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NASA CERES observations, 2000–2015 mean. Net radiation is incoming sunlight minus reflected shortwave and emitted longwave energy at the top of the atmosphere. Positive values indicate a radiative surplus.

Try a comparison

Turn Greenhouse on; distinguish surface emission from outgoing radiation at the top of the atmosphere. Check the top-of-atmosphere balance.

Reading the result

This simple energy-balance model isolates selected processes rather than representing the full atmosphere and climate system.

Film

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What Does the Atmosphere Do? Crash Course Geography #6 — Crash Course.

A common misunderstanding

Greenhouse gases mainly warm Earth by trapping incoming visible sunlight.

Much incoming solar radiation reaches the surface, where some is absorbed. The warmed surface emits thermal infrared radiation, which greenhouse gases and clouds absorb and emit. This exchange changes the surface temperature needed for the Earth system to balance absorbed solar energy with energy leaving for space.

Cases

Exam language

Albedo

The fraction of incoming sunlight reflected by a surface, expressed from zero to one or as a percentage. Fresh snow usually has a high albedo and dark soil a lower one. Reflected energy in watts per square metre is a flux, not albedo itself.

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CERES measures reflected shortwave energy in W m⁻². Albedo is the fraction of incoming sunlight reflected, so obtaining it requires dividing reflected flux by the corresponding incoming flux; the colour scale here is not albedo.

Shortwave

Radiation at the shorter wavelengths that carry most incoming solar energy, including visible light and parts of the ultraviolet and infrared spectrum. Earth’s much cooler surface emits mainly longwave radiation instead. Shortwave does not mean visible light alone.

Longwave

Thermal infrared radiation emitted by Earth’s surface and atmosphere. It generally has longer wavelengths than most incoming solar radiation. Greenhouse gases absorb and emit parts of this spectrum, influencing the rate at which energy escapes to space.

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NASA CERES, April 2015. Satellite observations map outgoing thermal radiation at the top of the atmosphere in W m⁻²; colder cloud tops generally emit less than warm clear-sky regions.

Greenhouse effect

Warming of a planet's surface and lower atmosphere because gases and clouds absorb and emit thermal infrared radiation, affecting the loss of energy to space.

Energy budget

An accounting of energy entering and leaving a system, such as Earth or a patch of ground. A persistent imbalance changes stored energy and can cause warming or cooling. A surface budget also includes evaporation and sensible heat transfers.

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Absorption

The transfer of radiation into a material, increasing its internal energy. Dark ground often absorbs more sunlight than bright snow. Absorption differs from reflection, which sends radiation away, and transmission, which lets it pass through.

Emission

The release of radiation by matter. Earth’s surface and atmosphere emit thermal infrared radiation at temperatures typical of this planet. This differs from reflection, which redirects incoming radiation without first absorbing it.

Insolation

Incoming solar radiation received at a surface. Its amount depends on the angle of the Sun, daylight duration and atmospheric conditions. Insolation is an energy input; air temperature also depends on energy losses, storage and transport.

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NASA SDO observes the solar photosphere and sunspots. The Sun supplies incoming solar radiation (insolation). The solar constant is irradiance near 1 AU on a plane perpendicular to the rays, about 1,361 W m⁻²; it is not measured by this visible-light photograph.

Process0.40Albedo0.30