
\def\V{{\bf v}}
\def\ave#1{\overline{#1}}
\def\mave#1{\tilde{#1}}
\def\q{c}

\begin{frame}
 \frametitle{Diffusive or local formulations for the PBL}


\begin{equation}\nonumber
\ave{w'\q'} = -K_z \frac{\partial \q}{\partial z} 
\hspace{.1\textwidth}{\bf\longrightarrow}\hspace{.1\textwidth}
\dt{\q}= \frac{\partial}{\partial z}
\dep{K_z \frac{\partial \q}{\partial z}}
\end{equation}

\begin{itemize}
\item Analogy with molecular viscosity\\
 (Brownian motion $\leftrightarrow$ turbulence)
\item Down-gradient fluxes.
\item Turbulence acts as a "mixing"
\end{itemize}




\end{frame}
