For the last 60 years, theoretical models have struggled to explain the observed level of tidal dissipation in bodies with substantial convective envelopes, such as giant planets and solar type stars. In this talk, we review these models and show that they break down when tides are rapid, that is, when the tidal period is short compared to the convective turnover timescale. We propose a new formalism applicable in this regime. Assuming that tides transfer their energy to the convective flow, this formalism yields values for the tidal dissipation factor of Jupiter and Saturn, as well as for the circularization periods of solar-type binaries and extrasolar planets, in good overall agreement with observations. Lastly, we show that the phase lag and the tidal dissipation factor Q vary by orders of magnitude throughout a gaseous envelope, and we define average quantities that can be directly compared with observational data.
