\begin{table}%T1
\caption{\label{tab1}Summary of the initial physical parameters characterizing the
unperturbed ambient medium and the spherical cloud.}
\small%\centering
\par
\begin{tabular}{lccc}
\hline
\hline
 & Temperature~ & Density~~~ & Cloud radius \\
\hline
\noalign{\smallskip}
{  ISM} & $10^4$ K & $0.1$ cm$^{-3}$ & -- \\
{ Cloud} & $10^3$ K & $1.0$ cm$^{-3}$ & 1 pc \\
\hline
\end{tabular}
\end{table}