Sounding Plugin - for paraglider pilots
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@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 -
I tend to agree with @matikru that the green dry adiabat seems too optimistic.
Not only in stable days, but also in well mixed days.
Although the core might start at the ground a few degrees hotter than the surrounding air; by the time it reaches the top of the CBL, there is no difference in temperature for the thermal as a whole, and it is humidity that keeps "pushing" upwards.Now we are on the off season in the southern hemisphere, but will compare to reality in the flying season.
Of course I am aware we are talking forecasts, and there is always uncertainty and error, but I think the green line adds to that error on the optimistic side.
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"@matikru The green line starts at air temperature + some constant (4 or 5C if I remember correctly)."
It looks like you add 3 degrees: https://github.com/vicb/windy-plugin-sounding/blob/ce22dc08d0d436fee4024ab54dc1642bf6762369/src/containers/containers.js#L28
A 2 degrees shift seems to match fairly well with the thermal top overlay, within a few 100 feet.
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@vicb Tanks
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@gkikas-lgpz
The scale in the bottom right is an approximate scale that uses the standard height levels used in aviation like
950hPa / 2 000ft / 600m
850hPa / 5 000ft / 1500m
700hPa / 10 000ft / 3000m
300 hPa / 30 000 ft / 9000m
etcc
These are approximately equal and used for easy conversion between different unit. However they are not exact.
In fact heights of pressure levels changes with different weather conditions. eg cooler temps have pressure levels closer to the ground as the air is denser.
More info can be found here https://en.wikipedia.org/wiki/International_Standard_AtmosphereAnyway the scale on the left is the model calculated height taking account of the meteo conditions (i think at least).
I am pretty sure that the scale on the windy map on the right is the correct values at the "model pressure height" which is an approximate height in m or feet.@gkikas-lgpz said in Sounding Plugin - for paraglider pilots:
..... at lower levels
point "B" marks the temp. at 600 hPa (13800 ft, FL140)
but the diagram shows 12000 ft (1800ft off). -
@vicb
Hi, your plug in is great, I love it. However I really struggle to use it on a mobile device which has already the windy app (I'm only using a mobile device for my paragliding forecast). I know I need to use a web browser but still, I need to upload the plug in each time I want to use it and sometimes it opens automatically the app instead of the web browser. I know it's a lot of work but is there a chance to have this amazing plugin working on the app someday?
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@Garba74 unfortunately this is a limitation due to the way the windy app is designed. I don't think plugins will ever work in the app.
Using the shortcut url windy.com/plugins/windy-plugin-sounding makes loading the plugin less tedious.
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@vicb maybe you can add some of the features here to your plug-in. I have the code behind it, a Perl script I think.
https://www.topaflyers.com/weather/soundings/drfsl.cgi?STATION=34.21%2C-117.32
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@aeolusforever what would you like to see added?
The plugin is open source (https://github.com/vicb/windy-plugin-sounding) you can even submit a PR if you want to.
I would love to get help with the development of the plugin. I have many ideas and not enough time. If anybody reading this want to help, please ping me. You need to know or want to learn frontend. -
@vicb you bet, thx for pointing to the repos, will try to get my head around it. Time’s the scarce resource and I’d rather be flying. ;-)
Where do you keep those ideas, like a feature list or part of a buglist in GH?
I like the yellow lines showing cape and potential thermal altitude and there are many more that could benefit from a one glance indication like the cloud base line. -
I have released v4.0.0 of the plugin yesterday.
It's now called flyXC soundings.
There are many improvements to the UI and even more changes under the hood.
I have written a longer post on the flyXC facebook page.
I'm pasting the last sections of the post below:
There are a few ways you can help the project:
- the README linked above is succinct. I would love some help with writing a nicer documentation
- you can also contribute code if there a feature you would like to see added - if you do not know how to code, you can still contribute ideas
- lastly you can sponsor the project. While the sounding plugin (as well as flyxc.app) is open source, it's nice to get some money to compensate the hours spent developing it
Do not hesitate to message me if you want to help.
Many thanks to windy.com for their awesome website and maintaining the plugin framework. Many thanks to John Kealy, his SkewT plugin released in 2019 was a great source of inspiration.
