Thermodynamic diagram; skew-T log-p diagram; tephigram কী?

A thermodynamic diagram is a chart whose coordinates are functions of the pressure and the temperature, on which isobars, isotherms, dry adiabats, moist adiabats and lines of constant saturation mixing ratio are printed, and on which a sounding is plotted as two curves, its temperature and its dew point. On a skew-T log-p diagram the vertical coordinate is $-\ln p$ and the horizontal one is $T + k\ln(p_0/p)$, so that isobars are horizontal and isotherms are straight lines slanting up to the right. A tephigram uses the temperature and the entropy per unit mass $c_p\ln\theta$ as coordinates, so that isotherms and dry adiabats are perpendicular straight lines.