Unconfirmed ASP4 - Ground fog layer not appearing any longer

Hello everybody!

I noticed that I haven't seen a ground fog layer since ASP4.
When I think about my flights in P3Dv2/v3 with ActiveSky Next and Active Sky 2016 (but I'm not sure anymore!), you often saw these great fog layers.
For example:

When I used the standard P3D weather theme "Fogged In" a few days ago - just for a test flight - I realized that P3D can still do that!

Now my question:
Is it possible, to implement this feature again in ASP4?
It shouldn't be to difficult to depict those fog layers, depending on the difference between Temperature and Dewpoint...

EDIT: Don't want to create another thread (maybe could also someone change the thread title... ), but there are also a few more ideas which could be added:

- Visibility Reductions in rain and snow conditions, as well as feedback effects (like small fog layers, especially over forest areas, after rain on a warm day)

- Visibility Reductions due to heat

- Using historical weather data to create actual weather (i.e. storms and rain on the day before, actual weather clear -> clean air and good visibility)

- Local wind effects ("Sudden" change of wind direction around the canary islands between 1500-3000 ft; trade wind circulation; sea-onshore-breeze system

- Local variable winds due to terrain or ^ local wind effects override METAR, (https://www.researchgate.net/profile/Jean-Claude_Ruel/publication/264887620_Effect_of_topography_on_wind_behaviour_in_a_complex_terrain/links/54007cb40cf2194bc29ae3a4/Effect-of-topography-on-wind-behaviour-in-a-complex-terrain.pdf)

- Smoother wind direction changes

- Turbulence due to strongly changing winds between to levels (i.e. 260/04 kts at Surface, but 040/24 kts at 3000 ft AGL)

- Interpolation over the rain areas, so areas with constant rain - below nimbostratus clouds - are possible

(If you need any informations regarding the depiction or the physics behind that, I would be glad if I could help!)

Thank you very much in advance!
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Beta Team Member
Thank you for posting Matthias. I will have a look and report back to you and the developers if I find anything.


Beta Team Member
Hello Matthias,

ASP4 does at least 2 things already. Fog is generated based on the difference between Temperature and Dewpoint and there is visibility reduction due to heat with a haze effect.

I have checked and as far as I can tell there is fog when I apply it. I set a flight at LOWI and set the temp/dew point to 13/02 and I did recreate fog. Have you tried clearing your shader cache? The issue may be caused by other weather programs or shader presets especially if you have upgraded to Prepar3D v4.5, applying presets will overwrite the contents of the ShaderHLSL folder. We can have a look at your settings, please log onto the HiFi support portal (http://support.hifitechinc.com) and log a support ticket, be sure to copy the URL from this forum post and include it in the ticket request. Please include most recent session logs, with Active Sky (only) running press the "Logs" button and save the AS_Log_Export.txt and attach to your ticket request.

The support site requires a separate login from the forum. Please note that you cannot login with your forum credentials, you will have to create a new account.

METAR LOWI 271720Z VRB02KT 9000 -RA SCT000 BKN010 13/02 Q1009 RMK EDITED WEATHER

I will send your suggestions over to the developers for consideration.

Thank you once again.
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Hi Robert,

thank you for your answer.
That ASP4 already depicts the fog on the basse of Dewpoint/Temperature is great, also the "heat haze effect".

Regarding the fog:
I don't believe that it's my system, because I haven't seen pictures of the ground fog layers in other forums since quite a time.
Maybe I wrote it a little misleading!

What I mean is the ground fog layer, from which low hills or skyscrapers look out.
The foggy conditions itself are working perfect, but these very flat ground fog layers (which you can see in my pictures #1, 3, 4) seem to be missing.
On your screenshot it seems that you have solved this by using Stratus clouds, but on my screenshots above volumetric fog is used.

As I wrote, if you need anything regarding the depcition or the physics behind that, don't hesitate to ask me!


Beta Team Member
Hello Matthias,

I was using ASCA together with ASP4, maybe that is why fog was visible on my simulator. I am running ASCA in "Global Automatic" mode.
Yes, me too.
I just took 2 screenshots:
The first one, with the METAR you posted, looks pretty much the same like the screenshot you have shown:

... And that's what I mean, the fog layer which is near the ground:


New member
Sorry for reviving an old thread but is there any development on this?
I'd love to have a low-laying fog/ reduced visibility. I requested the same feature myself some time ago.