Cold weather and pressure surfaces...

[cagarini]

We all know this is one of the features modeled in PSX, and I recall sometime ago, maybe somewhere along 2013 while Hardy was still working on PSX 1.0 he once posted at the old forum some question regarding this particular side of the "From High to Low" ( the T side ) being modeled in other desktop flight simulators...

Well MSFS and derivates, as well as X-Plane don't model this. For sure they do model density, but not the "collapse" of the geopotential surfaces under cold air masses -meaning that, for a given constant QNH, there is no difference in the pressure lapse rate between very cold air masses and hot air masses...

But, it's nice to know that, for instance, Flight Gear's Advanced Weather mode also models this the effect, and, when two years ago I started diverting towards Combat Flight simulation platforms after feeling so disappointed with the lack of detail and accuracy in MSFS and X-Plane in as far as flight, systems and weather modeling, among other features, go, I found that the two combat flight simulators I use also very nicely model the effects of Temperature in pressure lapse rates.

DCS World and IL2 Battle of Stalingrad have Summmer and Winter ( Spring and Autumn in il2 too ) maps, and the weather parameters such as Temperature, Pressure, Lows and Highs ( in DCS ), etc... can be set to match any RW situation.

Under low temperature scenarios they do exhibit the "straightening" / "shrink" of the geopotential levels / troposphere, and this also affects some aircraft systems like the turbocharger stages used on ww2 fighters, that change from low to high blower modes based on barometric pressure, and so, kick in lower in cold Winter scenarios than in hot Summer days for an identical QNH...

What no sim that I know of already simulates is the effect of moist on air and it's density. Indeed, in all of the sims I have used and tested, even those that allow users to set precipitation levels, cloud formations, and even T / Td, no change in performance and effective density altitude can be noticed based on the T / Td rate, as IRL...
Just a curiosity, even if it is not directly related to the 744 - sorry for that :-)