Mastering The Skew-T Diagram

(6 min)

There are fundamental properties of air that drive the weather you care about as a pilot. Their interrelation is the foundation for understanding weather, and isn’t covered in the typical instrument pilot ground school.

(12 min)

The Skew-T’s matrix of lines and color actually make sense once you get a step-by-step explanation, including how weather observations (radiosondes) get mapped onto a single base diagram.

(10 min)

Lapse rates, buoyancy, and stability predict the vertical motion of air that drives most adverse weather. These concepts can all be understood with intuitive analogies.

(17 min)

The standard change in temperature with altitude isn’t constant — but it can be read right off the Skew-T if you know how. These are the dry and moist adiabatic lapse rates that you may have heard about, but will now understand.

(13 min)

By understanding the rules governing rising air, known as parcel theory, you can predict cloud bases, tops, and potential for trouble right off the Skew-T diagram. There’s far more to it than just looking where temperature and dewpoint meet.

(20 min)

Simple terms and stability indices reduce the atmosphere to a single number that can often mislead. See where these numbers come from and how reading their change in the vertical reveals far more about the conditions than you’d expect.

(7 min)

The words “unstable air” often raise a red flag during that preflight weather briefing. But it shouldn’t in certain situations, such in this combination of factors on the Skew-T, Convective Outlook, and 500-mb chart.

(7 min)

There are many numerical weather prediction models that drive forecast data, but only a couple of them are the right choice for pilots. These are the important ones, including their coverage area and update frequency.

(12 min)

Most pilots access the Skew-T diagram on the web through the RUC sounding Java tool, but the same pilots might only know what a fraction of the options mean. Learn which options matter and how to use them.

(13 min)

Learning the “secret” features and extra data that are only a mouse click away is how savvy pilots get the most from the RUC sounding Java tool. Don’t just wonder why extra lines appear when you click. Master them instead.

(23 min)

A deeper understanding of using the Skew-T for bases, tops, and layers in between comes from dissecting specific examples, including foggy mornings, cumulus versus stratus clouds, wind shifts, and the effect of rain.

(10 min)

A temperature inversion is obvious on a Skew-T, but there’s also a second factor the chart reveals which is necessary for fog. In addition, clear air temperature inversions can hint at non-convective, low-level wind shear.

(17 min)

There are great tools for predicting the potential and severity of icing. However, those tools look at broad areas rather than specific routes or locations. Use the Skew-T to better understand the icing picture at specific points and altitudes.

(8 min)

Predicting potential turbulence is an unsung strength of the Skew-T. It just takes understanding how three factors work together to promote turbulence or prevent it. The vertical profile even shows where to find the smooth ride.