altitude of 5,000 feet above MSL. That may not appear  to be useful; however, this is where the dynamics  of the application come into play. If the computer  cursor is moved over the graphic part of the diagram,  indicators as to the specific information for that  altitude may be seen (not depicted in  Figure 4-35 ).  A pilot may be able to get information for varying  altitudes as close at 125 feet apart, depending on the  resolution of the original sounding information. There is a tutorial available to fully explain the data  interpretation of the Skew T plot at www.met.tamu.edu/class/ ATMO151/tut/sound/soundmain.html. Some of the information that may be derived from the Skew- T, using the example in  Figure 4-35: There is a wealth of information that may be derived from  the Skew-T plot (or “sounding,” as it may be referred to), but  this discussion will be limited to those features of immediate  interest to the average balloon pilot. weather sites; perhaps the easiest to use is rucsoundings.noaa. gov. The appropriate plot for any of the reporting sites can  be found by typing in the closest reporting station identifier  (usually an airport), and allowing the graphic to load.  •  The two lines running vertically through the center  of the graphic (red and blue) show the temperature  and dew point at ascending pressure altitudes. The  temperature is always plotted to the right of the dew  point because temperature is almost always greater  than the dew point temperature.  •  The right side margin shows wind speed and direction,  using the standard “barbed” system common in  weather reporting. The scale (in this case, 0 to 40  knots) can be changed, but this setting provides the  best resolution.  •  The left margin of the chart indicates the pressure  altitude for a particular reading. Pressure altitude  readings correspond generally to certain altitudes. For  example, the reading at 850 mb equates roughly to an  Velocity Azimuth display (VAD) winds are derived from  the output of the 160 WSR-88 radar sites located throughout  the United States. These radar systems are used by weather  professionals to produce many different products, including  the weather radar depictions found on many of the web sites  previously discussed, as well as various television station  weather reporting.  [Figure 4-36] The WSR-88 radar systems can be configured to produce  radar returns from dust and other particulate matter that may  be in the air. These radar returns can be processed to indicate  wind direction and speed at different altitudes. VAD winds  are generally reported in 1,000 foot increments, although at  Velocity Azimuth Display (VAD)Winds $_{Figure 4-35.}$  Example of a Skew-T plot. 4-35