Regression: Cloud thermals lost strength

[f16e66o]

The thermals connected to clouds have lost strength over the course of the past few Sim Updates.

At the moment we have to set up unrealistic conditions with very dense and high clouds to find good enough conditions to fly gliders.

In Sim Update 9 gliders were able to use clouds to identify thermals and fly long distances.
After SU10, 11 and 12 beta, we have lost the ability to use reasonably sized clouds to identify thermals when gliding.

Regression of cloud thermal strength from SU9 - 10 - 11/12

In the real world there is no linear connection between thermal strength and cloud density / height. Good thermals are often found under reasonably sized Cumululs clouds (see green graph).

Graphics created by @ANRI8496, using data measured in the sim with the weather debug tool.

Examples

Great thermal soaring day in real life:

Clouds we have to use in MSFS to fly gliders:

Clouds producing good thermals in the leading Gliding simulator: Condor2

What Gliders want in the sim:

We need to be able to use clouds as thermal identifiers in live weather / realistic weather preset scenarios.

Suggestion:

Change the calculation of updrafts below clouds to produce stronger thermals under smaller clouds, similar to how it was in SU9.

[DensestSnail693]

Voted … and turbulence slider or not I would expect to be tossed around a lot more once close to or within major clouds as per some earlier presets (that came with early versions of the Discus2c)

[flyndive]

I do have a couple of concerns with Anri’s proposed model. My intent is for this to be constructive criticism.

1. Thermals can exist with a cloud layer height (the distance between the cloud base and the top of the cloud) <6000 ft. I’ve soared IRL in moderate thermals quite a few times with Cumulus with cloud layer height of approx a thousand ft. Typical Cumulous cloud height is a few thousand ft, and the graph should reflect this.

2. There is actually a connection of thermal strength and cloud layer height, although not necessarily linearly as there are a lot of complexities involved (atmospheric stability, forming vs disintegrating, etc). Anri’s model proposes a factor 0.7 max for an ~8000 ft cloud height (as an example). Reality is that taller cloud heights would have much stronger lift, especially considering the strength of a towering Cumulonimbus potential drafts of 40+ m/s. I believe with the in-game max thermic lift limitation, Anri’s graph is probably the best that can be done for now (other than Point 1 above). Ideally, max thermic lift should be closer to 40-45 m/s with the graph updated accordingly at that time.

If they haven’t already, MSFS should really hire a meteorologist to work with those with solid real world gliding/flying experience sim flyers to devise a proper thermal model that is simple enough to be implemented into the game. There are some real-world cloud models to learn from (LES, CRM, SCM) which could be considered.

[Pieter2427]

What is your turbulence setting set to?

[N316TS]

@f16e66o , please do not delete the bug template when you fill out a bug report.

[f16e66o]

Turbulence setting is set to realistic.

To elaborate some more, what we (glider pilots) ask for is NOT a boost in strength of cloud thermals across the board.

The big storm clouds already produce great amounts of updrafts (aka thermals, not to be confused with turbulence)

It’s the small clouds (up to ~8000 ft bottom to top, <2 density) that have no measurable thermals attached to them.

In SU9 we could still find some lift below smaller clouds.
Unfortunately every following SU made the situation worse for glider pilots.

Note:
The graphics in the first post were made before the vertical wind (ft/min) limit was removed in SU12b.
So the curve shall not be interpreted literally, as there is no more Maximum vertical wind.
But it still shows the drastic lack of vertical wind below small clouds, which is still the case and is the core issue.

When comparing data from real life glider flights in common weather (resembling the few clouds stock preset in the sim), there is a huge difference to the cloud thermals we find (or rather dont find) in the sim.

And we are strictly talking about cloud thermals here. NOT the heat only thermals, of which there exist way too many, and which we hope will be significantly reduced (see "heat only" lift adjustment in SU12 Beta is an improvement but needs strength adjustment as well as altitude - #12 by FF403 )

It all boils down to the issue that we want to fly in realistic looking conditions and experience realistic amounts of thermals below clouds. Which is currently not the case.

Sorry @N316TS
here’s the added info from the bug template

Thank you for using the Bug section, using templates provided will greatly help the team reproducing the issue and ease the process of fixing it.

Are you using Developer Mode or made changes in it?

No

Have you disabled/removed all your mods and addons?

Yes

Brief description of the issue:

There is no thermic activity below small couds, only under huge clouds.

Provide Screenshot(s)/video(s) of the issue encountered:

See first post

Provide coordinates (DevMode > Options > Display position)

this is independent from exact location

Provide time & date of the observed Weather issue

Tested in Summer on Northern hemisphere.

Detailed steps to reproduce the issue encountered:

load a glider flight in the middle of the Ocean (to exclude the heat only thermals) some time in June, at noon and select the “Few clouds” weather preset. Note that when flying below clouds there are no thermals below them. Only when increasing the cloud top altitude and increasing the density, thermals start to show up. Even when testing over land, all the measurable thermals are not attached to clouds, but rather are generated from the surface.

PC specs and/or peripheral set up if relevant:

not relevant

Are you using DX11 or DX12?

DX11

Are you using DLSS?

Yes

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For anyone who wants to contribute on this issue, Click on the button below to use this template:

Do you have the same issue if you follow the OP’s steps to reproduce it?

Provide extra information to complete the original description of the issue:

If relevant, provide additional screenshots/video:

[DensestSnail693]

@f16e66o

Tested in Summer on Northern hemisphere

As stated I’m all for these improvements but mostly in live weather and changing dates simply is not live so I would rather chase the sun if I had to. Presets I’m sure will get their own treatment so I think there should be a clear distinction within this thread … I do realise you have quoted the few clouds preset.

[f16e66o]

This issue affects both live weather and presets.

The “Few Clouds” Preset was just mentioned as a reproducible test scenario.

It’s the underlying formula of how all the variables of the atmospheric simulation work together that needs adjusting.

Currently there is a big bias towards “heat only” thermals dominating all the thermic activity.
Whereas “cloud thermals” can only be found under huge clouds (both in presets and live weahter).

In real life chances to find a thermal are much higher below cumulus clouds, rather than a “blue hole”.
(Of course this depends on a large amount of factors IRL, but assuming a typical thermal soaring day)
In the sim the opposite is the case.

This is why a large amount of real world glider pilots dismiss MSFS at the moment, and is what we are hoping gets fixed as Jorg Neumann promised in an interview.

[DensestSnail693]

I agree with all you say I just wanted to say that if they can nail it in live then the presets should be a sinch … I wouldn’t want the devs to think we’d be happy with just the latter

[ANRI8496]

If you rely on my graph, then the maximum is about 2100 ft/min, and for the height (thickness) of the cloud layer 3000 ft (8000-5000) with a coefficient of 0.7, the desired thermal velocity is about 1500 ft/min.
Given the large number of dependencies for cloud thermals (coverage, dispersion, wind speed, temperature, precipitation, cloud layer height, cloud base height, and others), we want to see the right and beautiful clouds in good thermal weather and at the same time have the desired lift speed in the thermal. Moreover, over the sea, excluding the thermals of the earth and the elevator over the ridge. You need to fix all the dependencies.

[MSGamerTag01]

Do you have the same issue if you follow the OP’s steps to reproduce it?

YES

Provide extra information to complete the original description of the issue:

Behind the MSFS simulated ‘cloud lift’ is clearly a complicated formula including the density, base-to-top altitude, wind strength(??) but as the OP states the combination of these factors over the recent sim updates has resulted in a REDUCTION of lift in the range we’d expect for ‘normal’ Summer cumulus, e.g. 6000-foot cloud heights and a density of 1. Setting more extreme settings in SU12 Beta can give adequate lift but significantly impacts the visual appeal of the cloudscape.

[unbeneva]

I like to try to do cross-country thermal tasks in live weather. But at the moment it is close to impossible even on days that are in real life very good soaring conditions at my local gliding club. On these days the weather is fairly accurate in-sim, with small cumulus not too different from the weather-cam at the field - however there is not enough lift under the simulated cumulus in the sim to do a realistic distance.

I haven’t seen a day in live weather yet with the sorts of clouds required in a preset to produce flyable thermals.

On a side note - it would be great if thermals didn’t depend on the rendered cloud density at all, so we could have ‘blue’ thermals and do cross country thermal flights on blue days. As others have said, in the real world, the look of the cloud is related to the humidity, the strength of the thermals is driven by the temperature gradient (lapse rate). In dry arid regions it’s very common to get incredibly big and strong thermals with absolutely no clouds.

[GliderGuyBen]

Great point Neva, the comments I see in these threads from RL soaring pilots tend to be drowned out a little by suggested models trying to build thermals around Cloud size, height and depth etc. That is a back to front approach and as every soaring pilot knows, the cloud is simply a result of relative air temperature and dew point.
Thermals exist with or without clouds so building a “thermal” model around clouds will always be flawed.
The thermals dont get stronger because the cloud gets bigger… the cloud gets bigger cause the thermal gets stronger.

In essence all the information needed to build a thermal model exists if you look at Skew-T and Temperature trace diagrams - this will tell you the expected thermal strength, cloud base, height, Convective available potential energy etc.

To this point, there are many tools already using this information to very accurately predict soaring weather (Skysight, RASP, Windy) using freely available MET information.
To me it would make perfect sense if you wanted to build a live weather model, you should be looking at this information.
To build a weather model where you can select the type of day you want, you should be adjusting the basic variables such as temp, dew point, inversion and cape.

[Ephedrin87]

@ANRI8496

the desired thermal velocity is about 1500 ft/min.

That‘s about 8m/s… where is that supposed to be? Namibia?!

In Germany I barely see 3m/s

[ANRI8496]

We are talking about the maximum vertical velocity in thermal depending on the height of the cloud layer.
If we take into account that the vertical velocity in the thermal also depends on several factors, then we are unlikely to find an ideal coincidence of their maximum values. Therefore, it is quite normal to meet a “normal” cloud thermal at a speed of 400-600 ft/min (2-3 m/s).

[ANRI8496]

I wonder how many years will pass until the developers understand the need and create a new weather engine?

[GliderGuyBen]

Here is the way to calcuate what you are referring to Anri… otherwise we are just making stuff up

svr_parameters.pdf

[GliderGuyBen]

@ANRI8496

Therefore, it is quite normal to meet a “normal” cloud thermal at a speed of 400-600 ft/min (2-3 m/s).

This completely depends on the environmental factors of the day and cannot be generalised like this. Normal could be 2-4kts, or normal could be 7-10kts simply depending on time of year at a bare minimum, thus heat on the ground.

[DensestSnail693]

I sometimes think Asobo are trying too hard in guessing gliding conditions and what might be a better approach is a tool that allows experienced glider pilots to interactively plot areas and expected thermal and cloud behaviour in places that they fly and once agreed among other local pilots uploaded for inclusion of the world map. Likely is it would have to be additional to Asobo’s brave but not always accurate model which IMO is possibly not so editable on a local scale. That means we would probably need to dumb down the default with turbulence set low and then stick to the edited areas but they can always be expanded. Anyway I think this would be better than what we have currently.

Thunks?

[SSCGeorg]

The problem we are describing here is that “normal clouds” have 0 lift in msfs all the time.
Whereas they had some lift before SU 10.