tephigram

A tephigram is one of four thermodynamic diagrams commonly used in weather analysis and forecasting.

He introduced the air pressure unit millibar, as well as the tephigram, a diagram of temperature changes.

Wind barbs are often plotted at the side of a tephigram to indicate the winds at different heights.

With the hodograph and thermodynamic diagrams like the tephigram, meteorologists can calculate:

In the tephigram, isotherms are straight and have a 45 degree inclination to the right while isobars are horizontal and have a slight curve.

The tephigram was invented by Napier Shaw in 1915 and is used primarily in the United Kingdom and Canada.

In 1947, N. Herlofson proposed a modification to the emagram which allows straight, horizontal isobars, and provides for a large angle between isotherms and dry adiabats, similar to that in the tephigram.

In doing so, however, it sacrifices the equal-area requirements (from the original Clausius-Clapeyron relation) that are satisfied in two of the other diagrams frequently used (the Skew-T log-P diagram and the Tephigram).