Ridge thermals severely interfere with wind over terrain

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Vertigo
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Location: Belgium

Re: Ridge thermals severely interfere with wind over terrain

Post by Vertigo » Sat Jan 25, 2025 10:21 am

Ran another test, I wanted to see the effect of wind speed. I ended up with lower than intended actual windspeeds even with 50kmh in the notam because of the wind shadow of the mountains to the east.

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With those low (local) wind speeds, the angles look much more believable and more in line with the fluid dynamic simulation. The wind speed also has almost no effect on the measured slope. I see no problems in this test.

Again, I have no opinion on the accuracy of the wind field / windspeed in condor's model, Im just a dude that learned to draw triangles, and the angle of those triangles is perfectly believable here. The problem seems to be with steeper slopes/more wind, as I already suspected. The fact the angle seems to flatten out with increased wind speeds (contrary to the models wiek sent me) also hints at this, but that could just be measurement error, Im actually surprised my results are this close.

As for the distance to the mountain argument. In both this and the previous test, im about 1-2 wingspans from a 1500+m mountain. If you plot that on the simulation model, its basically a few pixels away from the mountain, where the airflow follows the mountain slope perfectly. As it did (close enough) in this test. In the previous test, the angle I measured was more in line with a distance away from the mountain equivalent to the mountain height. Small, wingspan-scale distances from the mountain might, probably should, affect windspeed, and thereby lift, but thats not what Im testing. For the angle its not a credible explanation. A limitation in condor's physics model when it comes to strong updrafts seems much more likely, and if so, Im more than happy to live with it, Im not asking for this to be changed, Im just drawing the triangles. FWIW Id much rather see breeze or rotors implemented one day.

havet865
Posts: 177
Joined: Mon Feb 12, 2018 11:35 am

Re: Ridge thermals severely interfere with wind over terrain

Post by havet865 » Mon Jan 27, 2025 12:37 pm

A glider pilot replicated his flight IRL in Condor 3.
The ceiling could be set lower, but it is actually pretty amazing to see that both varios are playing together at the same moment.

Are you convinced by it?


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Pit_R
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Re: Ridge thermals severely interfere with wind over terrain

Post by Pit_R » Wed Jan 29, 2025 4:53 pm

Hello!
Cool discussion...
Consider using Thermal Helper to get a better understanding of what's going on out there and what the thermals actually look like on the slopes. :)
No matter where you go... There you are...

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timbaeyens
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Re: Ridge thermals severely interfere with wind over terrain

Post by timbaeyens » Thu Jan 30, 2025 11:53 am

Repeating myself obviously; one day we might have valley (anabatic) winds included into the already very nice weather model of C3.
Depending on the mountain range orientation, time of year, etc, one should be able to expect an additional wind speed of around 10-20 km/h on slopes.
TT

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