I am trying to figure out about making clouds. For instance I can choose what kind of cloud, base and max altitude of cloud and what type of precipitation.  There is a box that says cloud thickness and can type in a number from 0 to I think like 9000 or 99000.  I can't remember off the top of my head.  If I put 0 does that mean the cloud is transparent and the higher the number the more dense the cloud is?  Has anybody ever messed with this setting?

Hi,

 

Cloud thickness is relevant to stratus clouds only and controls the height of the cloud.  Note that visible thickness (the actual thickness as seen in the sim) is usually quite a bit less than "configured thickness".  

 

Cumulus/Cumulonimbus clouds are not controllable for thickness.  They use a fixed 3D model chosen by FSX/P3D depending on the base height and type.

 

If you are manually creating weather or editing existing weather, it is recommended to use around 4000ft thickness for most layers, regardless of type.  You can experiment but keep the above notes in mind.  When not manually creating/editing weather, ASN automatically decides on height based on weather parameters (temperature, dewpoint, air stability, etc.) for stratus clouds.

Hope that helps!