Navigation

    Windy Community

    • Register
    • Login
    • Search
    • Unread
    • Categories
    • Groups
    • Go to windy.com

    "Surface" temperature/wind doesnt show earth's surface values

    Your Feedback and Suggestions
    3
    25
    4624
    Loading More Posts
    • Oldest to Newest
    • Newest to Oldest
    • Most Votes
    Reply
    • Reply as topic
    Log in to reply
    This topic has been deleted. Only users with topic management privileges can see it.
    • idefix37
      idefix37 Sailor Moderator @Gkikas LGPZ last edited by idefix37

      @Gkikas-LGPZ
      thanks

      1 Reply Last reply Reply Quote 0
      • Gkikas LGPZ
        Gkikas LGPZ Moderator @idefix37 last edited by

        @idefix37
        You said: "We have here the same problem, with -9ºC in Chamonix (1050m) and -11ºC on top of Mont-Blanc (4850m) !".

        I made a small research and I provide you the data and conclusions
        (for ECMWF model).
        Chamonix: model's "surface" =2137m, elevation=1036m (Δ= 1101)
        Mont-Blanc:model's "surface" =2265m, elevation=4808m (Δ= - 2543)
        Temperature adjustment
        Chamonix: +7,1C
        Mont-Blanc: -16,5 C.
        Those "adjustments" take into account Standard Atmosphere's lapse rate (6,5/1000m).
        In the real world, the lapse rate may vary from 9,8 °C/km in dry air
        to around 5 °C/km for moist air (into clouds).

        Hope it helps

        Gkikas LGPZ S idefix37 3 Replies Last reply Reply Quote 0
        • Gkikas LGPZ
          Gkikas LGPZ Moderator @Gkikas LGPZ last edited by

          ... in the same way (adjustments in ºC) ...
          for Vienna: +0,2 Innsbruck:+3,9 Praha: +0,4
          Olympus Mt.peak (2917m), Greece: -10

          1 Reply Last reply Reply Quote 0
          • S
            sPhoenix @Gkikas LGPZ | Premium last edited by idefix37

            @Gkikas-LGPZ

            Wouldn't it be even more accurate to use the result of the model for the exact elevation?

            So for example Mont Blanc: The delta between ECMWF model elevation and real elevation:1101m:

            So to get the estimated temperature/wind at the summit: use the closest calcuated value to 1101m above model surface. That's certainly also not 100% correct, because it doesn't take surface effects into account, but maybe more accurate than to assume ISA.
            It don't have access to the ECMWF data, but here a snapshot from NEMS4 sounding for Mont blanc:
            0_1516617214983_Capture.JPG
            The NEMS4 model surface seems to be at ca 3200m according to this sounding, temperature around -5°C.
            At 4800m it shows like -15°C. So a delta of -10°C in this case.

            Regards,
            Simon

            Gkikas LGPZ 2 Replies Last reply Reply Quote 0
            • Gkikas LGPZ
              Gkikas LGPZ Moderator @sPhoenix last edited by

              @sphoenix
              For Mont Blanc the Δ is 2543m

              Gkikas LGPZ 1 Reply Last reply Reply Quote 0
              • Gkikas LGPZ
                Gkikas LGPZ Moderator @Gkikas LGPZ last edited by

                @sPhoenix
                At the "sounding" :
                3200m ... -5°C
                4800m ... -15°C
                4800-3200=1600m ..... ΔT=10
                10/1600 = 6,25/1000m = ISA (almost !)

                1 Reply Last reply Reply Quote 0
                • Gkikas LGPZ
                  Gkikas LGPZ Moderator @sPhoenix last edited by

                  @sphoenix
                  Nice sounding! Is freely available ?

                  S 1 Reply Last reply Reply Quote 0
                  • S
                    sPhoenix @Gkikas LGPZ | Premium last edited by idefix37

                    @Gkikas-LGPZ

                    Yes almost ISA in this case, but just an example. But in most cases the ISA temperature delta would be good enough problably.

                    This graph is from meteblue, it's only available for point+ subscriber i think.

                    Regards,
                    Simon

                    Gkikas LGPZ 1 Reply Last reply Reply Quote 0
                    • Gkikas LGPZ
                      Gkikas LGPZ Moderator @sPhoenix last edited by

                      @sphoenix
                      Thank you

                      1 Reply Last reply Reply Quote 0
                      • idefix37
                        idefix37 Sailor Moderator @Gkikas LGPZ last edited by idefix37

                        @Gkikas-LGPZ
                        Thank you. I took the example of Chamonix and Mont-Blanc temperatures just to underline the wrong temperature display by global models in mountain areas. You give the way to know the exact temperature, fine. But for me, just a quick look to the airgram, as you explained before, it’s enough precision.
                        What I have found through these questions, that’s the worse terrain resolution of the global models compared to there atmospheric resolution. And this is not obvious, as Windy show a very precise terrain resolution, we expect the same precision from global models, but that’s impossible !

                        1 Reply Last reply Reply Quote 1
                        • First post
                          Last post
                        Windyty, S.E. - all rights reserved. Powered by excellent NodeBB
                        NodeBB & contributors, OSM & contributors, HERE maps
                        Terms and Conditions     Privacy Policy