
A legend identifying the particular sounding is essential if the sounding plot is to be useful. Always put the sounding location (WMO station number or three letter identifier), as well as the time (UTC) and date.
It is sometimes instructive to plot two soundings on the same Skew-T chart; for instance, comparing sounding changes over time at a particular location, or comparing soundings from two different NWP model runs. While there are several conventions for plotting multiple soundings, it is most important to plot them in such a way that you can distinguish them (e.g., solid/dashed lines, different colors, etc.). Typically, winds for different soundings are plotted on different wind staffs (appropriately labeled), although in some cases they could also be distinguished using different colors.
For electronically plotted soundings, various calculated quantities, levels, and indices are plotted on the right-hand side of the diagram.