VIL Density:

VIL Density is simply the VIL divided by the echo top (m) and multiplied by 1000 in
order to express the result as g m-3. The importance of VIL Density is its use in
quickly identifying thunderstorms with high reflectivities relative to their
height. Such thunderstorms often contain hail cores, and as VIL Density increases,
the hail core tends to be deeper, more intense, and the resulting hail sizes tend
to be larger (Amburn 1996).