Freezing Alt and Freezing Alt Isolines Very Different
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I’ve noticed that the Graphical depiction of Freezing Altitude differs significantly from the Freezing Alt isolines particularly when an isoline is crossing an area of changing terrain (such as a mountain range). Is one AGL and one is MSL? It would be nice if the alt reference was noted on the app for all altitude figures (Freezing Alt, Cloud bases, cloud alts, etc).
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@tembek Hi, could you please provide a screenshot example?
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@korina   image url)
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@tembek I’m trying to upload a screen shot but keep getting an error message. Is it because I’m a new user?
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@korina ok so I’m uploading two screenshots. Each highlighting a different position on the same 5400’ Freezing Alt Isoline.
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@korina I don’t know why the second image is so poor but it shows the same area with the pointer moved along the same 5400ft isoline to a position west of the mountains.
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@tembek
Freezing altitude in Windy is AGL. It would be better to call it Freezing heights.
https://community.windy.com/topic/3643/clouds-bases/8?_=1614847163124
But isolines plotting is so smoothed that they don't match so well with terrain altitudes, less than the map.
Same with isobars and map pressure. -
@idefix37 the isolines appear to me to be MSL while the graphical display seems to be AGL. If you look at Isolines even crossing the Rockies you don’t see any real impact of surface elevation. Again I wish the reference was specified in the name of the option in the App. For example instead of Freezing Alt, Say Freezing Alt MSL. Without knowing the reference the information can be dangerous for a pilot since it can be off several thousand or even 10,000 ft.
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@tembek
Sorry, I am not an aviation specialist but I see over the rockies the freezing isolines match approximatively the map display.
At the picker point both are shown at 0ft, so they seem consistent and isolines can’t be amsl. As said before there are possibly locations where isolines don’t give precise values because they are smoothed, more than the model orography. Hope aviation specialists confirm.
