I posted this question in the HiFi forum as well but since I believe there are more real world drivers in here I hope it's OK to post this question here as well. After all I do all my flying in the NGX so in a way it's related :wink:In Active Sky 2012 there is an option called Visibility Graduation and Smoothing and what it does is described below from the help file for AS 2012.　Graduation CeilingWhen Visibility Graduation and Smoothing is enabled, this value controls the altitude (in feet AGL) that the Maximum Upper Visibility should be depicted. For example, at 27000ft AGL, visibility will slowly increase from the surface to the maximum at 27000ft. A minimum of 5000 and maximum of 90000 is acceptable.By default this value is set to 8000 feet but to me that seems a bit low so if a RL pilot could comment on this it would be much appreciated!TIA,

Edited January 23, 201214 yr by WebMaximus

I'd say it's highly variable. There is a definite layer of "local" air that you see as you descend into cities. As you pass into it, there is often a brownish tint to the horizon. Areas of high pressure have more haze than low. 8,000 seems like a good number. On hazy summer days it might be in to 20,000 and higher.Have fun.

On those hazy summer days with a high pressure system sitting around, the haze layer is pretty clearly defined as if you are flying over a brown ocean. Some days it is really cool when scattered cumulus look like ice burgs floating in the brown sea with the submerged part brown and the column above the haze bright white. Pretty cool. Never gonna see that in MSFS.

On those hazy summer days with a high pressure system sitting around, the haze layer is pretty clearly defined as if you are flying over a brown ocean. Some days it is really cool when scattered cumulus look like ice burgs floating in the brown sea with the submerged part brown and the column above the haze bright white. Pretty cool. Never gonna see that in MSFS.

And we, the Human "fishes", move around and breath in that Brown Ocean !!! It's disgusting !!!It's not nearly so noticable on the ground, (unless you live in LA ! ) but from up in the air, it's a real eye opener.

Thanks guys for your interesting input!Maybe a value around 10K then during winter season and around 20K during summer would be fairly good and realistic values...or maybe about 15K as an all year around compromise :(

This is a highly variable value related to the temperature inversion point. You can see these well illustrated on aerological diagrams (http://www.bom.gov.au/aviation/observations/aerological-diagrams) as the place where the temperature line stagnates or increases with height. Not sure if these effects are simulated I the weather engines?CheersJames

That's an interesting site, thanks for the link!