> however just try to modify the wind kt within the local weather tile gui,
> iget nasal error

After some reflection and a similar problem discussed in the forum, I
think I start to see a potential misunderstanding here.

In an integrated weather system, there's no way to 'just modify the wind'
because everything is tied with everything else.

Take the case of a weather front: That's an airmass moving against another
airmass with different properties, since air movement is the wind, the
front is roughly perpendicular to the wind, i.e. you can see by looking at
a cloud photograph how the large-scale air movement is even without
observing movement of individual clouds. Thus, if you see a weather front
and want to change the wind by 60 degrees, you're not asking for the
windfield to be changed only, you are asking for the whole visible cloud
configuration to be rotated by 60 degrees.

You could think of using a rotation matrix, recompute all coordinates in
local Cartesian approximation and be done. Unfortunately, weather feels
terrain. So you might rotate clouds from a low region into a high region
and vice versa, thus creating implausible layer altitudes above ground -
which you don't want. Therefore you need to recompute the terrain
elevation and correct the altitude of every cloud you rotate.

Unfortunately you're still not done, because for convective clouds you may
change the whole distribution pattern - you may rotate clouds from a city
(where many convective clouds are expected) to open water (where only few
can occur) - thus you have to recompute the whole interaction of the
system of thermals and convective clouds with the terrain.

So now we have to recompute essentially all cloud positions in potentially
120x120 km area just because we changed the wind. If you have dynamical
weather on, in addition you need to rotate a lot of plane, wind and view
co-moving coordinate systems, internal weather and windfield interpolation
points and a lot of other important technical, though invisible stuff.

Basically, you need to recompute almost everything.

Which is why Local Weather Tiles is a launcher gui, not a runtime
configurable thing. I guess it's the same reason that Flightgear doesn't
allow to change the plane at runtime. If you want different weather, you
need to end the running system and start a new one. The gui is actually
supposed to tell you that, but that may not happen in every instance.

I suspect that you have tried to use the gui as if it would allow runtime
changes, have discovered a way that doesn't trigger the warning, and that
then leads to errors.

Cheers,

* Thorsten


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