XP12 Weather and Clouds

[coastaldriver 941]

Laminar have not specifically stated that they have adopted True Sky Clouds but looking closely at the clouds and general weather issues, I am struck by the very close similarity to True Sky that LM introduced into P3DV5. All the same problems are evident. Particularly after a long flight from Australia to the Philippines today. 

It seems that the cloud displayed below F200 is generally ok and more than quite acceptable but it seems to me that neither Laminar or LM have managed to deal with the issue of high level cloud or Cirrus clouds succesfully, well not yet. 

So here is an out of the window screenshot at FL310

In a life time of real world aviation I have never seen buildups like this at FL's, this cloud on this occasion was also producing streaming rain from time to time, an impossibility in the real world. Cirrus cloud forms above F200 it is in thin sheets and while it fits the met definition of cloud (visible aggregate of atmospheric moisture) it is frozen water droplets in other words ICE. At the most it may be 100 to 300 ft thick and you would never I repeat never, see streaming rain of any sort from this type of cloud. You may get some light rime ice but generally that is about all. 

I have not yet seen a good mushroom thunderhead cumulonimbus shown in P3D or XP12. 

Here is another shot This is a bit better but not really a good likeness of Cirrus Cloud. Cirrus cloud by definition is "feathery' or like feathers, light hair like cloud whisps. 

And the real thing:

I am not really confident that proper Cirrus is achievable with True Sky, LM could not make it happen and none of the various mods that I tried to Volumetric Cloud in P3D did it either.  Guess we shall see!

 

[Murmur 3,984]

LR is indeed working on improving clouds, and specifically cirrus clouds. Mentioned here:

https://www.x-plane.com/kb/x-plane-12-00-release-notes/

[coastaldriver 941]

Well we can hope, Knowing how True Sky works - the parameters are there but unless you get access to the True Sky SDK or tool kit there is only so much a general user can do with it. I have always thought it had great potential but the implementation by flight sim has been flawed. 

Maybe LR are indeed the ones to sort it out - they have done a great job with the sim in general and a lot of features that have eluded the other simulators!

Does not lessen my adoption of XP as my primary sim after years of LM and P3DV5 it is very very good indeed. Suits my needs!

Edited January 13, 2023 by coastaldriver

[Bjoern 1,196]

Ray marching, the underlying technique used for cloud rendering in XP12, P3Dv5, MSFS20 and DCS is openly documented. So all these clouds fundamentally look alike, with each platform tweaking the end result to its preference.

XP12 is on the right track. Its sky and weather looks a whole lot better than they did in XP11.

Edited January 13, 2023 by Bjoern

[Franz007 647]

1 hour ago, Bjoern said:

XP12 is on the right track.

I can agree 100%! This sim gives a fantastic immersion and many happy moments. Sure there are some work to do on clouds and weather but they are absolutely on the right track. It could become in 1-2 years the sim i’ve ever deeamed of if they open soon their weather-API for devs that will allow 3D-weather-radars, then improving the clouds, bringing light reflections on clouds during night and making metars match a bit better. And the default airports with the weather effects are just amazing.

I absolutely love the new weather-engine even if not perfect. Seeing the clouds moving with the time and not being rebuilt every 10 minutes like in XP11 is a huge improvment. I am thrilled! I didn’t open XP11 and MSFS since the first beta-release 😃

[coastaldriver 941]

Could not agree more Bjoern there are so many innovative changes in XP12 I could almost get excited about it (Chuckle). They have a way to go with the weather and by that I mean the way the weather engine or processes are interpolating and translating NOAA data into what you see in the sim.

At low level it is of course well done (not perfect but impressive - see my post on a flight in the LR C172 from EGOV. The problem for all of them is the data itself because above about F150 ( where detailed forecasts and data stop) the data shifts to pressure/temperature related data sets because at altitude the primary analysis and physical movement of air is along temperature gradients (It moves or circulates the same as pressure - high to low) and the demarcation line the tropopause shifts from being very high at the equator to mid latitudes to low (about F320 in high latitudes) If you look at any grid map for high altitude flight you get wind direction, speed and temperature and maybe a rough outline of possible severe weather (CAT and TS's) and not much else. That is a major programming challenge to show this data in a visual way such as a cloud formation and especially cirrus which in my humble opinion has more different presentations, albiet in 3 main classifications, than any other cloud you see in the sky. A low level forecast or actual is way more detailed as to cloud type its base, distribution and tops as well as winds etc so much easier to work with!

[coastaldriver 941]

Bjoern - you given any thought to redoing your neat little weather radar addon for FSX/P3D for XP or too dificult? All I know is all my old programming tricks and methods are basically useless in XP as its architecture is so different - big learning curve all right!

 

Edited January 13, 2023 by coastaldriver

[jcomm 6,141]

They ( LR ) have to fix the "turbulence" and the whole blend between forecast and observation + sigmet data.

There are inconsistencies in all of these at present state. 

Turbulence is one of the most evident problems for any user. It's present under meteo conditions that do not justify it, it's overdone in most situations, it's always of the same type.

Data gathered from the GRIBs isn't properly blend with METAR fields. Under some circumstances there were huge discrepancies between the wind and temp as well as visibility and cloud coverage + precipitation observed in a sim session using real world weather and the actual weather at given places.

It looks like it was less noticeable in the first betas, and got worst in the last one I tried (before rc1 which I haven't used).

Would be great to have the SDK ready for 3pd to do their Magic too... I miss HiFi...

[coastaldriver 941]

The screenshots were taken of cloud I did not mention the bizarre temps the sim weather engine was producing and its effects on the turbine engine modelling.

For the first portion of the flight the aircraft (B720) would not climb above F260. At that altitude the temp was being given as +3C then later it would drop to -19C then rise again. Alimeter the whole flight was set for the standard 1013 pressure level for above F180 and remained unchanged. The aircraft was not producing lift or thrust properly but the fuel burn was going through the roof. I had to hold 100% N1 at F260 and it only gave me a IAS of M0,60 sometimes M0,55. Approaching the equator the temp dropped again and I finally managed to nurse the aeroplane up to F310 but it would never go any higher. At the altitude I was seeing an OAT of 0.C the -10C and then -19C and so it went all the way into the Northern Hemisphere to the Phillipines. It was only at mid latitudes in the Northern Hemisphere that the temp started to drop again and the aircraft increased in speed (it never went above M0.72) and the fuel burn went down. I actually discussed the issue with the modeller/designer and he was as perplexed as I was as the temps and performance. The LR aircraft parameters were actually correct in terms of interpreting the temps etc. This is the sort of performance you would get at sea level or low altitude with these sorts of temps. 

Now to put that into context these were temperature anomalies of ISA +47 to ISA +50, now in my whole flying career ISA +10 or ISA+20 was possible and catered for in the aircraft manuals to set power and fuel flows. I have never seen ISA +50 at FL310, nor rain. I have no idea how the LR weather engine was interpreting the data it was getting or how it could be so out of whack with the real world! IN fact there was no performance data for any of the aircraft I flew for temps above 42C the manufacturer never expected anybody to operate the aeroplane in those conditions and never produced it - that meant if you were on the ground somewhere and the temps hit above 42C then you could not fly! That could happen a lot in Western Australia in summer so you always planned to go in and get out early before the ground temps went above what the performance manuals allowed for. But then that was real life!

[Bjoern 1,196]

14 hours ago, coastaldriver said:

Bjoern - you given any thought to redoing your neat little weather radar addon for FSX/P3D for XP or too dificult? All I know is all my old programming tricks and methods are basically useless in XP as its architecture is so different - big learning curve all right!

 

Nope. FSX' XML and XP's Lua is as different as Chinese from any Roman language. Besides, XP supports a weather radar overlay (if only for cloud layers) on MFDs out of the box. Implementing that is completely up to the aircraft author though.

The only of my FSX things that survived in spirit and is MITool, but it's completely different code and still far from complete.

[coastaldriver 941]

Alas that is what I thought. XP is a very different beast indeed, still the bonus is it is well away from the MS strangle hold on things flight simulated.