What are Altitude Rings in a Weather Radar?

Apparently, i am the last avionics technician on the face of the earth that did not know what “Altitude Rings” are.

Here is the Honeywell training Blah Blah :

Altitude rings Its a PPT


Altitude rings  Or here  for a PDF.

It is a arc shaped return that results from the radar bouncing off of the top of the radome when the tilt is all the way up.