SkewT-logP Diagram


This thermodynamic diagram displays plots of temperature (red), dew point temperature (green), and wind speed (kt)/direction with respect to pressure. Pressure is denoted by the black horizontal lines (labeled on left in mb), and isotherms are "skewed" as dashed pink lines from lower left to upper right (labeled on bottom in degrees C). Unsaturated parcel ascent is represented by the solid pink curves from lower right to upper left (dry adiabats), and saturated parcel ascent is represented by the dashed brown curve emanating from the most unstable parcel level. The environmental wet bulb temperature profile (i.e., the temperature that would result from evaporational cooling of each level to saturation) is plotted in dark cyan between the temperature and dew point traces.The effects of ice processes or water loading in saturated ascent are not accounted for in this diagram.

Levels above ground level are plotted for reference in red along the left side of the diagram, while the surface parcel height (m) above mean sea level is plotted in parentheses. Also, the freezing line (0 oC) and the -20 C isotherm are highlighted in dark blue.

The NSHARP program uses the virtual temperature when computing values related to latent instability.