I think I found the problem and possible work around and it appears to be an LM problem and I've notified them.
None of the Client, Content, Scenery update installers will replace the VolumetricClouds.cfg file for the older P3D V5.1 version with the newer one that contains the [Global] section and possibly other changes.
Delete Generated Files will NOT delete the VolumetricClouds.cfg file.
As a result this entire section is missing from VolumetricClouds.cfg and/or other changes to [Cumulonimbus], [Cirrus], [Stratus], [Cumulus] are not there. The only way to work around this is to manually delete the VolumetricClouds.cfg and then start P3D which will then regenerate this file with the correct sections.
I'm almost certain this is the cause for users indicating "missing" clouds/weather, especially those using HiFi ASP3D. My other concern is there possibly anything else not updating correctly from the installers and/or not being deleted with "Delete Generated Files" (which is a prepar3d.exe command line option)?
[Global]
render_grid_x_km_low = 0.3
render_grid_x_km_med = 0.3
render_grid_x_km_high = 0.2
render_grid_x_km_ultra = 0.15
render_grid_z_km_low = 3.0
render_grid_z_km_med = 3.0
render_grid_z_km_high = 3.0
render_grid_z_km_ultra = 3.0
cloud_resolution_low = 256
cloud_resolution_med = 512
cloud_resolution_high = 512
cloud_resolution_ultra = 768
max_cloud_distance_km_low = 200
max_cloud_distance_km_med = 250
max_cloud_distance_km_high = 300
max_cloud_distance_km_ultra = 350
num_slices_low = 128
num_slices_med = 128
num_slices_high = 128
num_slices_ultra = 128
cloud_shadow_strength = 1.5
cloud_shadow_range_km_low = 100.0
cloud_shadow_range_km_med = 175.0
cloud_shadow_range_km_high = 250.0
cloud_shadow_range_km_ultra = 300.0
cloud_shadow_texture_size_low = 256
cloud_shadow_texture_size_med = 512
cloud_shadow_texture_size_high = 1024
cloud_shadow_texture_size_ultra = 2048
crepuscular_ray_strength = 1.0
edge_noise_wavelength_km = 2.5
worley_texture_size = 64
cell_noise_wavelength_km = 2.7
max_fractal_amplitude_km = 3
cloud_threshold_distance_km = 0.2
This entire section is missing, such that ONLY a full clean install of P3D will get the correct VolumetricClouds.cfg.
WORK AROUND is to manually delete VolumetricClouds.cfg location example: C:\Users\Rob\AppData\Roaming\Lockheed Martin\Prepar3D v5
Cheers, Rob.
