  All the studies of the interaction between tides and a convective flow assume
that the large scale tides can be described as a mean shear flow which is
damped by small scale fluctuating convective eddies. The convective Reynolds
stress is calculated using mixing length theory, accounting for a sharp
suppression of dissipation when the turnover timescale is larger than the tidal
period. This yields tidal dissipation rates several orders of magnitude too
small to account for the circularization periods of late-type binaries or the
tidal dissipation factor of giant planets. Here, we argue that the above
description is inconsistent, because fluctuations and mean flow should be
identified based on the timescale, not on the spatial scale, on which they
vary. Therefore, the standard picture should be reversed, with the fluctuations
being the tidal oscillations and the mean shear flow provided by the largest
convective eddies. We assume that energy is locally transferred from the tides
to the convective flow. Using this assumption, we obtain values for the tidal
$Q$ factor of Jupiter and Saturn and for the circularization periods of PMS
binaries in good agreement with observations. The timescales obtained with the
equilibrium tide approximation are however still 40 times too large to account
for the circularization periods of late-type binaries. For these systems, shear
in the tachocline or at the base of the convective zone may be the main cause
of tidal dissipation.
