cloud height derivations

1. cloud height from cloud base/top height

   symbol	description	unit	variable name
   \(z_{c}\)	cloud height (mid point)	\(m\)	cloud_height {:}
   \(z_{cb}\)	cloud base height	\(m\)	cloud_base_height {time}
   \(z_{ct}\)	cloud top height	\(m\)	cloud_top_height {time}

   The pattern : for the dimensions can represent {latitude,longitude}, {time}, {time,latitude,longitude}, or no dimensions at all.

   \[z_{c} = \frac{z_{ct} - z_{cb}}{2}\]