  Localized rain events have been found to follow power-law distributions over
several decades, suggesting parallels between precipitation and seismic
activity [O. Peters et al., PRL 88, 018701 (2002)]. Similar power laws can be
generated by treating raindrops as passive tracers advected by the velocity
field of a two-dimensional system of point vortices [R. Dickman, PRL 90, 108701
(2003)]. Here I review observational and theoretical aspects of fractal rain
distributions and chaotic advection, and present new results on tracer
distributions in the vortex model.
