\begin{table}%t2
\caption{Mean pulse height excess.}
\label{tab:spread}
%\centering
\small
\begin{tabular}{c c c c}
\hline \hline
&Cloudless&Nimbostratus&Thunderstorm\\
\hline
$\chi$&0.17&--0.15&1.27\\
\hline
\end{tabular}
\end{table}