  A weakly deformable droplet impinging on a rigid surface rebounds if the
surface is intrinsically hydrophobic or if the gas film trapped underneath the
droplet is able to keep the interfaces from touching. A simple, physically
motivated model inspired by analysis of droplets colliding with deformable
interfaces is proposed in order to investigate the dynamics of the rebound
process and the effects of gravity. The analysis yields estimates of the bounce
time that are in very good quantitative agreement with recent experimental data
(Okumura et. al., (2003)) and provides significant improvement over simple
scaling results.
