AoE Vertical Measurement

[Richelieu]

Hello everyone,  I found a few topics on vertical measurement, but nothing that specifically addressed measuring an AoE in three dimensions.  Do people generally treat AoE as infinitely tall cylinders, or as spheres centered around the origin.  For example, if i shoot a Cometstrike Scepter at the center of the base of a balewind vortex, would it hit the model on top if I only rolled a 1" range?

[heywoah_twitch]

Measuring base to base means literally that in real life, so it would factor in vertical height, just as climbing terrain counts vertical height. 

[Arkiham]

its a sphere. 

distance in all directions from the point of choosing.

can only be a sphere by logic.