New Weather Interface - Problem with wind layers

[Ralf T]

Dear Pete,

first, let me say thank you for your great FSUIPC Module. It accompanies my flightsimming hobby now since nearly 5 years. In this time I developed a weather generating program for my own personal use. But now I have a little problem, maybe you can help me.

I‘m using your new weather interface, and when I insert new wind layers, sometimes sth. odd is happening:

If you enter the following wind layers, i.e. in WeatherSet2 for an ICAO Station (i.e. EDDF)

10000ft, 10kt, Direction 90

20000ft, 10kt, Direction 80

you get the result

10000ft, 10kt, Direction 90

20000ft, 10kt, Direction 100

It seems, that when the wind direction is turning to the left with increasing layers, FS is adding the difference, instead of sustracting it. This happens only with ICAO Stations. With GLOB it is working right.

If you set GLOB only, the values, that are transferred to the (not set) ICAO Stations differ in the same way as described above from the GLOB setting.

Is there something you can do about this in your FSUIPC Module, to correct this?

Best regards

Ralf

[Pete Dowson]

I‘m using your new weather interface, and when I insert new wind layers, sometimes sth. odd is happening:

...

It seems, that when the wind direction is turning to the left with increasing layers, FS is adding the difference, instead of sustracting it. This happens only with ICAO Stations. With GLOB it is working right.

Congratulations. you have discovered the bug in FS which has been troubling us for months. There appears to be no way possible to set a Weather station with anti-clockwise wind direction changes as you climb, only clockwise. We think it is this problem which is contributing, maybe even causing, the sudden 180 degree windshifts folks experience. and this does occur with FS's own dowloads too.

Is there something you can do about this in your FSUIPC Module, to correct this?

No. FSUIPC is definitely sending the weather exactly as requested to FS. It is getting corrupted internally. We've found no way around this. The only solution apears to be to always set clockwise spiralling wind directions -- to keep to "realistic" wind directions at the specified altitudes, insert an extra layer half-way between such layers with the wind direction half way beteen the others in the clockwise direction.

I think this is what the main weather program authors will be experimenting with at the moment.

Regards,

Pete

[Highvolt]

Actually, if i remember my meteo theory lessons correctly, wind directions always rotate clockwise if you increase height.

On the southern hemisphere they rotate anti-clockwise

I remember it had something to do with the coriolis effect because the earth is spinning.

[Pete Dowson]

Actually, if i remember my meteo theory lessons correctly, wind directions always rotate clockwise if you increase height.

On the southern hemisphere they rotate anti-clockwise

I remember it had something to do with the coriolis effect because the earth is spinning.

Well, certainly depressions rotate one way (like water down a drain) and highs the other, but that's the general direction of the winds in any layer. I'm not sure it applies to the difference at different altitudes as such. The upper winds I think tend to have different causes than the lower ones, less to do with pressure differentials and more to do with night/day changes and, yes, coriolis I suppose.

Either way, I think this problem in FS has been checked in the Southern hemisphere and found to be the same, not reversed. But I'm not totally sure about that ...

Regards,

Pete

[Pete Dowson]

Actually, if i remember my meteo theory lessons correctly, wind directions always rotate clockwise if you increase height.

On the southern hemisphere they rotate anti-clockwise

I remember it had something to do with the coriolis effect because the earth is spinning.

Well, certainly depressions rotate one way (like water down a drain) and highs the other, but that's the general direction of the winds in any layer. I'm not sure it applies to the difference at different altitudes as such. The upper winds I think tend to have different causes than the lower ones, less to do with pressure differentials and more to do with night/day changes and, yes, coriolis I suppose.

Either way, I think this problem in FS has been checked in the Southern hemisphere and found to be the same, not reversed. But I'm not totally sure about that ...

Regards,

Pete

[Ralf T]

Hello Pete,

Thank you for your quick answers and sorry for not checking the older entries in the forum.

It seems, that I have to ajust the direction of my tradewinds to the rules of Microsoft :wink:; not really surprising...

So, I'll try the way the others go, entering intermediate layers.

Thank you again for the help and for your great work. Without the possibilities that FSUIPC opens to us, my FS hobby would be half that fun!

Best regards

Ralf

[Ralf T]

So, I thought a bit about a workaround for the problem:

If I use only 1 wind layer, in which I generate the conditions at the altitude, in which the plane is flying, I could get around this problem (the same way, as you did in former versions of FSUIPC)

The only problem seems to be, that there is at present no way, to give the "real" surface wind information for ATIS and runway selection to FS, as ist was possible in FS2k2 and the AWI with the adventure values.

Do you think, there is a way to give the surface winds to FS, independent of the settings in the 1. Wind Layer in GLOB or in ICAO? (maybe with sth. similar like the adventure variable in former versions?)

regards

Ralf

[Pete Dowson]

If I use only 1 wind layer, in which I generate the conditions at the altitude, in which the plane is flying, I could get around this problem (the same way, as you did in former versions of FSUIPC)

Yes, but watch out that you don't introduce small stutters each time you change it. The way FS2004 deals with weather is complex and each time a change is made is seems to need to re-interpolate using all the nearby weather stations -- not just three as in FS2000 and FS2002, but many! And for any weather change made through FSUIPC I currently have to give it a complete new weather structure.

I would love to find a way of by-passing all that and dealing directly with the weather at the aircraft, as I did in previous versions of FS. But alas many hours of hacking got me nowhere.

The only problem seems to be, that there is at present no way, to give the "real" surface wind information for ATIS and runway selection to FS, as ist was possible in FS2k2 and the AWI with the adventure values.

That was a fiddle in FSUIPC itself. You could set two wind layers, or maybe three if you need to go anti-clockwise. But experiment first in any case. I hope you don't get disappointed with the performance.

Regards,

Pete

[Ralf T]

That was a fiddle in FSUIPC itself. You could set two wind layers, or maybe three if you need to go anti-clockwise. But experiment first in any case. I hope you don't get disappointed with the performance.

Pete

So far I had no problems with the performance using one wind layer in GLOB and adjusting it to the 4 wind layers, my program generates. When crossing the border between 2 Layers I made changes to the GLOB setting every 2 seconds.

(This was my initial method dealing with the winds in FS2k and FS2k2, mach the same way, as you did)

The only problem with this is now, that when I approach an airport, FS chooses the momentary wind direction at my present altitude for the selection of the runway, since this is the only value set in FS (-> only one wind layer).

So what I would need is to give the surface wind independently to FS. With the AWI this was possible in FS2k2, but now this does not work anymore, even if I use the AWI.

Do you think, it might be possible to inject the surface wind value, that FS uses to determin the active runway and the ATIS independently from the actual weather settings? That would allow me to avoid the problem with multiple wind layers.

regards

Ralf

[Pete Dowson]

The only problem with this is now, that when I approach an airport, FS chooses the momentary wind direction at my present altitude for the selection of the runway, since this is the only value set in FS (-> only one wind layer).

So what I would need is to give the surface wind independently to FS. With the AWI this was possible in FS2k2, but now this does not work anymore, even if I use the AWI.

Do you think, it might be possible to inject the surface wind value, that FS uses to determin the active runway and the ATIS independently from the actual weather settings? That would allow me to avoid the problem with multiple wind layers.

No, I've no way of getting this sort of information to the ATC. I might be able to fiddle the ATIS, but I suspect not. I think the way both get their weather data has changed. I used to be able to intercept the call the ATIS made and overwrite the wind information.

I think your only solution is, knowing the ICAO of your destination, and assuming it is also a listed WX station (not all of them are), to set the local weather for your destination.

To make the ATC choose the correct runway you have to do this a good way out -- over 85 nm, the maximum radius at which FS seems to generate traffic. Once it has traffic assigned to a runway it won't change that assignment even if you change the wind -- not until you leave the area again (so it is out of range) and return.

Regards

Pete

[Ralf T]

Thank you for your help, Pete!

I'll try this out. If it doesn't work, I'll go the way the others go and adapt my wind generating routines to generate clockwise directions.

Best regards

Ralf