ENERGY BALANCE MODELS represent the First Law of Thermodynamics applied to a system. In climatology, energy balance models are used for the Earth-atmosphere system. This is a closed thermo-dynamic system because it does not exchange matter with the surrounding environment, or space. Energy balance models can be applied to the Earth-atmosphere systems for different timescales such as a year, day, or hour. Depending on the timescale, the models would produce an annual, daily, or hourly temperature of the Earth-atmosphere system. Also, the energy transfer processes, the energy cycle, [Page 370]could be either steady-state or transient processes. For steady-state models, the energy input is equal to the energy output in the system, resulting in a steady temperature that does not change with time. This assumption is ...