When can the reverse ISL be applied

[D.bunk01]

Lets say a character punched the sky which caused the clouds to disperse around that attack. the shockwave created from their punch spread out as it moved up but the area was still smaller than the bottom area of the cloud. cloud the reverse ISL still be used and have it be Area of the cloud/area of the shock wave*original value. Or would the wave need to have a larger area than the cloud? because going by what the formula is right now area of the larger object OR explosion/smaller object*original value. Here it says OR which to me sounds like the explosion doesnt need to be larger

 

[Golden_Void]

ISL finds the intensity of a source energy at different distances as it propagates outward.

The reverse finds the source energy if you know a destruction value at some distance away from the source.

Your specific question is confusing though so idk.