Time-height indicator
From Glossary of Meteorology
time–height indicator
(Abbreviated THI.) A type of radar display on which the reflectivity, Doppler velocity, or other properties of echoes are displayed as a function of time and height in rectangular coordinates.
The THI is ordinarily composed of successive observations with a vertically pointing radar beam. It may be an intensity-modulated display or may use a scale of colors to represent the values of the function displayed.