Why drop size distributions in sprays fit the Log-Normal?

Numerous drop size distributions in sprays fit the Log-Normal. This letter explains the physical origin of this fitting as the exponential growth of drop size diversity. Consequently, the standard deviation of the natural logarithm of drop size acquires physical meaning. The insights retrieved from this explanation include a demonstration that drop size histograms fitted by a Log-Normal should use variable size classes, and the interpretation of the stochastic nature of spray characteristics acquires greater physical meaning.