Effects on Weather

Sounding plotted on skew-T diagram showing shallow potentially unstable layer

The idea of potential instability and stability appears to be very simple and the criteria for them are certainly very easy to use. But the relation of these states to the resulting weather is very complex and not well understood. The classic example of the release of potential instability in severe convection is the lifting of an air mass characterized by rapid drying above a surface moist layer. This is similar to the example we just examined.

There are, however, many other layers with less-marked potential instability and the assessment of the type of weather that lifting will produce remains a challenge. For example, this sounding shows a shallow potentially-unstable layer with deep layers of potentially-stable air both above and below. When lifted to saturation, this layer may produce any of the following:

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