The values in the boxes are energy flows or fluxes in units of watts per square metre [W m^-2] and are based on the published energy budget.

The sun's output, averaged over the Earth's surface taking into account its curvature is 342 W m^-2 and 77 of those units are reflected or scattered back into space by the atmosphere including clouds and aerosols. Clouds are a special case of aerosols, particulate matter with sizes much greater than those of molecules. Other aerosols include droplets of sulfuric acid formed by the oxidation in the atmosphere of volatile sulfur compounds. These latter include dimethylsulfoxide [(CH₃)₂SO] which is a major effluent from plankton and sulfur dioxide which is emitted, now generally illegally, by industrial plants such as those that roast sulfide ores in the extraction of metals. The oxidant is generally thought to be the hydroxyl free radical, OH, which is produced when water molecules are photolyzed in the stratosphere by far-ultraviolet radiation. Molecules of the atmosphere are small enough to deflect incoming photons and scatter them in all directions, some photons being directed back into space.

In the passage of solar radiation through the atmosphere another 67 W m^-2 are absorbed by the greenhouse gases. Ten of those 67 are absorbed in the stratosphere, mainly by oxygen molecules which are photoloyzed [decomposed] and produce two oxygen atoms. O₂ ® 2O. The very reactive oxygen atoms combine with oxygen molecules to give ozone: O + O₂ ® O₃

This reaction is vital to life as we know it since the ozone absorbs most of the incoming ultraviolet radiation which would otherwise be incident upon the Earth's surface. There is a controversy about the 'ozone hole' which is another story! The 'hole' is not a hole as we understand the term, but is a region around the poles in which the concentration of ozone is considerably lower than that in the stratosphere generally. This is not surprising since only weak sunlight gets to those regions and the ozone concentration is somewhat dependent upon winds to replenish it.

The remaining sunlight which is transmitted by the atmosphere suffers another reflection at the surface to the extent of 30 W m^-2 and only 168 W m^-2 is absorbed by the surface.

The surface is further warmed by infrared radiation that is emitted downwards by the atmosphere. This 'downwelling' radiation amounts to 324 W m^-2

The surface and the immediate atmosphere do not continue to become warmer because of the solar and downwelling IR radiation, they have cooling mechanisms. There are three main ways of cooling the surface; 1. conduction and convection, 2. evaporation of water and 3. radiation. The first two mechanisms are lumped together in this model and represent non-radiative cooling of the surface and the warming of the atmosphere. The radiative cooling is by the emission of terrestrial IR radiation to the extent of 350 W m^-2 which is absorbed by the greenhouse gases and by 40 W m^-2 that sail through the IR window straight into space.

The final part of the model is the radiation to space from the components of the atmosphere of 195 W m^-2.

A link to the model: