HE Enhancement

The HE curve is used principally by weather offices in the western United States.  It provides good
enhancement of a wide variety of cloud types, but is somewhat complex, and may be difficult
to use at first.  It enhances low and middle level clouds common along the Pacific Coast of
North America in two separate gray shade ranges.  The freezing level is easily determined, an
advantage for aviation users concerned with icing.  Step wedge regions display very cold
infrared cloud top temperatures associated with thunderstorms and frontal systems in 5 degree
increments down to -60 C.  Two additional "repeat gray" segments define cloud top temperatures
colder than -60C.