File:Greenhouse Effect.svg

English: This figure is a simplified, schematic representation of the flows of energy between space, the atmosphere, and the Earth's surface, and shows how these flows combine to trap heat near the surface and create the greenhouse effect. Energy exchanges are expressed in watts per square meter (W/m²) and derived from Kiehl & Trenberth (1997). Complete figure: (http://www.cgd.ucar.edu/cas/abstracts/files/kevin1997_1.html UCAR.edu)

Suggested corrections:

• Change the 195 from "thermal radiation" to "atmospheric radiation" into space, as it does not include the 40 radiated from the surface.
• Change the "Greenhouse gas absorption: 350" to "Surface radiation absorbed/ captured by greenhouse gas: 350" or "Athmospheric absorption of surface radiation: 350" or "Greenhouse gas radiation absorption: 350" (see the Kiehl/Trenberth source). If this is not feasible due to space limitations it should possibly be explained in the image notes that the remaining grey part of the arrow stands for thermic energy transmission by convection of sensible and latent heat.)

The sun is responsible for virtually all energy that reaches the Earth's surface. Direct overhead sunlight at the top of the atmosphere provides 1366 W/m²; however, geometric effects and reflective surfaces limit the light which is absorbed at the typical location to an annual average of ~235 W/m². If this were the total heat received at the surface, then, neglecting changes in albedo, the Earth's surface would be expected to have an average temperature of -18 °C (Lashof 1989). Of the surface heat captured by the atmosphere, more than 75% can be attributed to the action of greenhouse gases that absorb thermal radiation emitted by the Earth's surface. The atmosphere in turn transfers the energy it receives both into space (38%) and back to the Earth's surface (62%), where the amount transferred in each direction depends on the thermal and density structure of the atmosphere. This process by which energy is recycled in the atmosphere to warm the Earth's surface is known as the greenhouse effect and is an essential piece of Earth's climate. Under stable conditions, the total amount of energy entering the system from solar radiation will exactly balance the amount being radiated into space, thus allowing the Earth to maintain a constant average temperature over time.

However, recent measurements indicate that the Earth is presently absorbing 0.85 ± 0.15 W/m² more than it emits into space (Hansen et al. 2005). An overwhelming majority of climate scientists believe that this asymmetry in the flow of energy has been significantly increased by human emissions of greenhouse gases [1]. This figure was created by Robert A. Rohde from published data and is part of the Global Warming Art project.