English: A Sankey diagram-inspired schematic of a zero-dimensional radiation-balance model for a planet in equilibrium with its parent star and the rest of space. Single-layers representing ordered interactions of shortwave solar radiation and thermal radiation with the planet's atmosphere and surface are included. Being absent of spatial dimensions, this model ordering defines a set of coupled equations that can be solved to investigate the sensitivity of global and long-term average temperatures to other parameters.

Mathematical expressions for the model parameters and radiation flows is conventional per following model references:

• ACS Climate Science Toolkit: https://www.acs.org/content/acs/en/climatescience/atmosphericwarming/multilayermodel.html
• METEO 469, Modelling of the Climate System (Mann and Gaudet): https://www.e-education.psu.edu/meteo469/node/198

A bond albedo combines the atmosphere and surface reflections of solar radiation. The planet surface also absorbs and radiates thermal energy as a perfect blackbody. These are reasonable simplifications for a planet such as Earth.
Energy storage and other modes of transfer (such as conduction, convection, latent heat) by the surface and/or atmosphere are not included. Direct absorption of shortwave solar radiation by the atmosphere is also assumed to be negligable. These are significant effects for a planet such as Earth, and indicate where caution is required when interpreting model results. Related Sankey diagrams that account for some of these effects are:

• NASA Energy Budget Poster (2010): https://commons.wikimedia.org/wiki/File:The-NASA-Earth%27s-Energy-Budget-Poster-Radiant-Energy-System-satellite-infrared-radiation-fluxes.jpg
• Kiehl and Trenberth (1997): https://commons.wikimedia.org/wiki/File:Figure_2.1_Global_average_energy_budget_of_Earth%E2%80%99s_atmosphere_(6080398732).jpg
• https://commons.wikimedia.org/wiki/File:Greenhouse_Effect.svg