Ignore:
Timestamp:
Sep 5, 2012 11:27:58 AM (9 years ago)
Author:
heinze
Message:

Update of cloud_physics.pdf

Location:
palm/trunk/DOC/tec/methods/cloud_physics
Files:
2 edited

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  • palm/trunk/DOC/tec/methods/cloud_physics/cloud_physics.tex

    r701 r988  
    4343\linebreak
    444414.12.2009
     45\linebreak
     46\linebreak
     47last update
     48\linebreak
     49\today
    4550\end{center}
    4651
     
    6267\end{itemize}
    6368The dynamical processes are covered by advection and diffusion and they are described by the implemented methods. For the consideration of the
    64 thermodynamical processes modifications are necessary in the thermodynamics of PALM . In doing so evaporation and condensation are treated as
     69thermodynamical processes modifications are necessary in the thermodynamics of PALM. In doing so evaporation and condensation are treated as
    6570adiabatic processes whereas precipitation and radiation are treated as diabatic processes. In the dry version of PALM the thermodynamic variable
    6671is the potential temperature $\theta$. The first law of thermodynamics provides the prognostic equation
     
    137142  -\frac{\partial \left(\overline u_{j} \overline q\right)}{\partial x_{j}}
    138143  -\frac{\partial\, \overline{u_{j}^{'} q^{'}}}{\partial x_{j}} 
    139   +\left(\frac{\partial \overline q}{\partial t}\right)_{\mathrm{RAD}}
     144  +\left(\frac{\partial \overline q}{\partial t}\right)_{\mathrm{PREC}}
    140145 \label{eq:total_water}
    141146\end{eqnarray}
     
    348353 \left(\frac{\partial \overline q}{\partial t}\right)_{\mathrm{PREC}} & = &
    349354  \begin{cases}
    350    \left(\overline q_{l}-\overline q_{l_{\mathrm{crit}}}\right)\cdot \tau &
     355   \left(\overline q_{l}-\overline q_{l_{\mathrm{crit}}}\right)/ \tau &
    351356   \quad\overline q_{l} > \overline q_{l_{\mathrm{crit}}} \\
    352357   0  & \quad\overline q_{l} \leq \overline q_{l_{\mathrm{crit}}}
     
    356361The precipitation leaves the grid volume immediately if the threshold of the liquid water content
    357362$\overline q_{l_{\mathrm{crit}}}=0.5\,\mathrm{g/kg}$ is exceeded. Hence, evaporation of the rain drops does not occur.
    358 $\tau$ is a time scale with a value of 0.001\,s.
     363$\tau$ is a time scale with a value of 1000\,s.
    359364\newline
    360365The influence of the precipitation on the temperature is as follows:
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