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.