  We investigate the interplay between substrate roughness and surrounding gas
pressure in controlling the dynamics of splashing when a liquid drop hits a dry
solid surface. We associate two distinct forms of splashing with each of these
control parameters: prompt splashing is due to surface roughness and corona
splashing is due to instabilities produced by the surrounding gas. The size
distribution of ejected droplets reveals the length scales of the underlying
droplet-creation process in both cases.
