Thermodynamic diagrams are diagrams used by scientists and engineers to represent the
thermodynamic states of a material (typically
fluid) and the consequences of manipulating this material. For instance, a temperature-
entropy diagram (T-s diagram) may be used to demonstrate the behavior of a fluid as it is changed by a compressor.
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A chart containing contours of pressure, temperature, moisture, and
potential temperature , all drawn relative to each other such that basic thermodynamic laws are satisfied. Such a chart typically is used to plot atmospheric
soundings , and to estimate potential changes in temperature, moisture, etc. if air were displaced vertically from a given level. A thermodynamic chart thus is a useful tool in diagnosing atmospheric
instability . (See sounding):