Temperature/Levels » Wet-Bulb Temperature (Tw) Skew-T Procedure
At a given pressure level, do the following:
- From the temperature, proceed up along a dry adiabat.
- From the temperature, proceed up along a dry adiabat.
- From the dewpoint proceed up along a mixing ratio line.
- From the dewpoint proceed up along a mixing ratio line.
- From where the two lines intersect, proceed down the saturation adiabat to the original level.
- From where the two lines intersect, proceed down the saturation adiabat to the original level.
In this example, air at 850 hPa with T = 20°C and Td = 0°C has a wet-bulb temperature of 10°C.
Recall that the definition on the previous page called for a process at constant pressure, which implies no vertical motion. Yet the skew-T procedure illustrated here requires the apparent lifting of an air parcel. This just illustrates that the skew-T is fundamentally a thermodynamic diagram that allows us to determine various thermodynamic properties graphically, as well as display sounding data and other vertical atmospheric profiles.