Cloud cover is defined as a layer over the terrain, with a bottom and top and density for each cell.
AreaProperty: clouds
layer-data...
This property is the degree of cloud cover over each cell.
A value of 0
corresponds to clear skies.
AreaProperty: cloud-bottoms
layer-data...
This property is the altitude above the ground of the bottoms of the clouds.
AreaProperty: cloud-heights
layer-data...
This property is the vertical thickness of the cloud cover in each cell.