humidity as a function of altitude and through the clouds

[Flying toaster]

Hello,

I am looking to simulate icing as a function of altitude, but I stumble across two small problems.

• Dewpoint has a fixed (harcoded to 0.002) lapse rate which means that relative humidity will at some point in a climb always get to 100% and remain there for the rest of the altitude profile. It so happens that in general around the tropopause, the air will largely dry out, and therefore that approximation could be completed for higher altitudes. Nothing that can´t be compensated with Nasal. Any cleaner option ?

• While reviewing the Simgear code to understand how the visual fogged out when entering a cloud I did not find a property in the tree that indicates that condition. This would be very convenient to simulate the icing hazard that clouds represent as far as icing is concerned. Did I miss something in the property tree that I could use ? I seem to remember a post that mentioned you could use visibility but the effective-visibility property does not seem to be influenced when crossing a cloud layer (which is pretty strange).

I haven´t looked very closely but, does anybody know if temperature inversion is simulated ?

Thank you in advance

Enrique

[wkitty42]

you might look at the c172p... it has both fogging and icing...

[Thorsten]

Nothing that can´t be compensated with Nasal. Any cleaner option ?

No, because the reality of it is really complicated, basically you'd need a real measurement across different altitudes to get this right, there's no way to model this from METAR or an assumption about the weather situation - this kind of thing is an input to real weather models.

(Guess what - I had the same question some 5 years ago and researched it...)

While reviewing the Simgear code to understand how the visual fogged out when entering a cloud I did not find a property in the tree that indicates that condition.

That'd be because AW is Nasal code rather than simgear code, and /environment/visibility is ultimately what enters the renderer (aka what you see), so...

I seem to remember a post that mentioned you could use visibility but the effective-visibility property does not seem to be influenced when crossing a cloud layer (which is pretty strange).

AW does this for the denser layers and larger clouds, but not for every whisp in the sky.

I haven´t looked very closely but, does anybody know if temperature inversion is simulated ?

Again, the real dynamics of a temperature profile is really complicated (it has to do with high atmosphere chemistry and absorption cross sections and such things) so usually this is input to weather modeling, not output.