20. Skew-T Log-p Diagram

Taking a deviation away from plotting data on two-dimensional maps, here we look to plot vertical profile data to understand aspects of the atmosphere that are important to stability, precipitation, and precipitation type. There are a number of different thermodynamic diagrams that are used in the sciences and engineering. In meteorology, these diagrams are used to plot a variety of different atmospheric parameters, all in a standard, easily accessible format and are used extensively in forecasting. In a number of ways they can be used to assess the vertical structure and stability of the atmosphere. The vertical profiles of temperature, dew-point temperature, and wind speed and direction can explain a lot about the nature of atmosphere and what types of weather may form in such an environment.

The data displayed in these diagrams are collected by radiosondes, which are instrumented platform with meteorological sensors and a radio transmitter that are carried aloft by a balloon. Radiosondes are released at selected NWS sites across the country at 0000 and 1200 UTC every day, as well as from sites around the world. Sometimes special radiosondes are released at 1800 UTC (or other times) on days when the risk of severe weather is especially high.

Stability is an important concept for understanding many atmospheric processes, but how can we assess the stability? The vertical stability of the atmosphere is determined by the vertical distribution of temperature, pressure, and wind speed and direction. These measurements are obtained by launching radiosondes with a big balloon. In this lab we will first review stability terminology and then discuss how we can plot our variables in a helpful fashion.