\begin{table}%t1 \par \caption {\label{clumps}Properties of the envelope convection zones in our~20 and 60~$\mso$ models of solar metallicity. These are the same models shown in the top panel of Figs.~\ref{20zsunsurf} and in~\ref{60zsunsurf}. The values in the table refer to $t$~=~\ttwenty for the 20~$\mso$ model and $t$~=~\tsixty for the 60~$\mso$ model.} \renewcommand{\footnoterule}{} %\centerline {\begin{tabular}{l c c c c c c c c c } \hline\hline $M$ \T & Zone & $\hp$ & $\vca$ & $\Delta M_{\rm conv}$$^a$ & $\Delta M_{\rm top}$$^b$ & $N_{\rm cells}$$^c$ & $\tau_{\rm turn}$$^d$ & $\tau_{\rm conv}$$^e$ & $ \dot{M}$ \\ $M_{\odot}$ \T & & $R_{\odot}$ & km~s$^{-1}$ & $M_{\odot}$ & $M_{\odot}$ & & days & days & $\mso ~\rm{ yr}^{-1}$ \\ \hline 20 & He & 0.025 & 0.08 & $7.6\times10^{-9}$ & $1.9\times10^{-9}$ & $1.8\times10^{5}$ & 2.5 & 38 & $7.3\times10^{-8} $ \\ 20 & Fe & 0.08 & 2.40 & $3.6\times10^{-6}$ & $5.8\times10^{-7}$ & $1.8\times10^{4}$ & 0.25 & 18~250 & $7.3\times10^{-8}$ \\ 60 & Fe & 0.24 & 2.25 & $1.6\times10^{-5}$ & $9.8\times10^{-7}$ & $8.5\times10^{3}$ & 0.83 & 1570 & $3.7\times10^{-6}$ \\ \hline \end{tabular}} \par \smallskip $^a$ {Mass contained in the convective region.} $^b$ {Mass in the radiative layer between the stellar surface and the upper boundary of the convective zone.} $^c$ {Expected number of convective cells, $N_{\rm cells}:= (R_{\star}/H_{\rm P})^2$.} $^d$ {Convective turnover time, $\tau_{\rm turn}:= H_{\rm P}/\vca$.} $^e$ {Time that a piece of stellar material spends inside a convective region, $\tau_{\rm conv}:= \Delta M_{\rm conv}/\dot M$.} \par \end{table}