Sounding Plugin - for paraglider pilots
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Hey @MarkRD could you please let me know what location and time lead to the bug ? I have problem to reproduce the issue.
The could base altitude that is see matches the actual altitude in my tests (when you hover on the graph you can see the altitude on the horizontal bar and the cloud base matches that at +/- 100m but that is due to rounding error).
What you pic shows is different. 3100m as no reason to be below 3000m.
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@vicb The location was S26 10'09'', E28 0'35''. Unfortunately, I don't know which GFS forecast time it was for exactly but it would have been for one of the hours yesterday (1st Oct 2020) - I'm not sure how to get the time slider to go back a day on windy.com.
I will keep an eye out for if I see something like it again (all my sounding plots today look fine with the cloud base altitude reflecting values within the vertical axis as one would expect). If I do see it again, I will add a comment on your issues page with more complete information (location, date, model, forecast hour etc) - apologies for that.
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@vicb I posted another instance I found on your github issue page. I hope it helps. I'm a bit suspicious that it happens with the same altitude again (in a different location).
I've only ever seen it happening with the GFS model, not ECWMF yet, if that is of any help.
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@MarkRD Thanks a lot.
As I replied on github you have identified a bug in the plugin. It comes from the fact that the relation between altitude and pressure is not linear.
I need some time to think about the best possible fix. Probably a few days.
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@vicb No rush! Thanks for a cool plugin.
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The plugin now works better on mobile and tablets.
As a reminder plugins do not work on the installed mobile apps but you can use them by loading windy in a web browser on your mobile or tablet.
Visit https://www.windy.com/plugins/windy-plugin-sounding to load the plugin on a mobile device.
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Excellent! Works well.
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@vicb
How do you select another location than the favorite, without closing the plugin ? -
@vicb
Sorry, I found it, it is still possible to open it via the picker -
Thanks for the nice feedback @rittels - and thanks for your help !
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Hey, I got a problem.
Dunno why but when I try to use your plugin the whole windy.com freezes: the forecast page & the forum page. I have disabled the AdBlock and allowed pop-ups windows.
Similar situation with Skew-t- it doesn't freeze but nothing is popping up.
Does anyone know how to make it run and is willing to help me?
!
edit: i cannot even upload a picture here :( link
edit: its something with my chrome, other browsers works ok for me -
@tomasz-w Hello, image upload size has a limit, try to upload a smaller picture.
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Hi, amazing plugin ;)
One question (sorry if a dummy one):
How do you determine where the green line starts on the ground?I see that "The green line shows the temperature of an ascending parcel" but why on the ground it has this particular temperature?
Is there some meteorological constant or formula based on which we know that a bubble would need this-or-that higher temperature than surrounding to start rising?
Correct me if I'm wrong, but to my mind, this starting point is crucial in understanding how strong and how high thermals will be, so I'm wondering (as a gliding pilot) how exactly to interpret this and how to actually know when during the day my lovely bubbles will start to rise.
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@matikru
It should be the temperature at 2m forecasted by the model used for the sounding -
@matikru The green line starts at air temperature + some constant (4 or 5C if I remember correctly).
Check a typical example:
You can see that the value of the constant usually doesn't matter that much for the days we are interested in. You have to remember that we look at a model which is an imperfect prediction plus the nature of the soil varies greatly inside a single cell of the model (cells are 9x9km for ECMWF).
In practice it works reasonably well. The air close to the ground doesn't usually get warmer as it would start rising.
If the cloud cover is thick it might be harder for the air temperature to become that warm.
If the temperature (red) and green line (parcel) slowly converge instead of being parallel, that could also be due to the poor resolution of the model (there are not that many points along the altitude axis).
Hope this helps.
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@vicb thanks for this clarification.
But, since as you noted "The air close to the ground doesn't usually get warmer as it would start rising" do I understand correctly that the green line should actually start (at the ground level) quite at the same temperature level that the red line starts?
So actually this 4-5 C constant is introduced just for better usability of the diagram, as this green and the red line would just overlap usually?
Btw - I get it now that considering model errors etc. it doesn't make such a difference, I just want to understand the logic behind.
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I'm thinking, isn't it that sometimes it will be quite misleading? In this example, it doesn't look like convection at all, no chance for cumulus, since dry adiabat is steeper than air temperature change.
But, looking at the green line starting 4-5 C higher than the red line there's this impression that there will be convection, even a cumulus is depicted at 800.Or am I missing something totally? :)
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Mostly what I mean is that the rising air don't get as warm as the ground.
I think that rising air typically needs a few more degree than the surrounding air to rise.
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@matikru yes you still need to interpret what you see. In your screenshot the air is stable (converging lines that I mentioned in a previous message) + there seems to be stratus where the blue line is close to the red line below 1000m
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@vicb
Cirrus at this altitude? You probably mean Stratus ?
https://community.windy.com/topic/9778/visual-difference-between-clouds?_=1617389340187
