How to Read a Skew-T


When you first look at a Skew-T, what do you see? There's nothing but a bunch of lines, right? Here is a quick explanation of what all those lines mean.

 

Figure 1. A sounding showing letters that correspond with the appropriate lines mentioned above.

Lapse Rates

Environmental lapse rate - The rate of decrease of temperature with height of the atmosphere surrounding the parcel (estimated as the lapse rate of the temperature curve mentioned in the last section).

Dry adiabatic lapse rate - The rate of decrease of temperature with height as an unsaturated parcel of air rises adiabatically (estimated as the lapse rate of the dry adiabat mentioned in the last section). Typically -9.8 ºC/km.

Moist adiabatic lapse rate - The rate of decrease of temperature with height as a saturated parcel of air rises pseudo-adiabatically (estimated as the lapse rate of the saturation adiabat mentioned in the last section). Can range from -4 ºC/km to -9 ºC/km but an average value is about -6 ºC/km.

Super adiabatic A condition in which the environmental lapse rate is steeper than the dry adiabats. The most common location for super adiabatic layers is right above the ground on a sunny day.

 

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Page References

American Meteorological Society. Glossary of Meteorology Online.  Allen Press.  2005.  http://amsglossary.allenpress.com/glossary

Department of Atmospheric Science University of Wyoming . Use of Skew T-log p diagram . Air Weather Service (MAC), United States Air Force. (1969).

Wallace, John and Peter Hobbs. Atmospheric Science An Introductory Survey. Elsevier Science: USA . (1977).