Is there a key or explanation to decoding the "meteogram" view?



  • Is there a guide to interpreting the meteogram available? I see this question has already been asked (though misspelled) but has received no reply for over a year.


  • Sailor

    @orome
    There is no user guide available. So if you have precise questions about the Meteogram we will try to answer them.



  • I'm not the original poster, but I have some questions about the meteogram view.

    283c02be-3250-4d71-b925-7ac3cdcfd0b5-image.png

    1. In the above image, what is the meaning of the lines like "800h 2km 6400ft"? I assume the last two are the elevation in meters and feet (do we need both??). But what is 800h? Is that 800hPa, the pressure at that elevation?

    2. How about the line above that one with the entry "FL100"? What does the mean?

    3. And a final question. I will often see a partly cloudy designation in the second line of the meteogram (as at 3 & 6 PM in the screen shot), but there will be no clouds shown at any elevation in the Clouds section. I do see the cloud base at those times as being 13K and 20K. Is it just that the clouds are too high to be depicted on the graph? I have also seen cases where there is rain predicted but no clouds show on the Clouds section of the meteogram. What's up with that?

    I'm an amateur astronomer and the cloud forecast if particularly important to me.


  • Sailor

    @btschumy
    Hi,
    Some answers to your questions:

    1. Yes it is important to have the altitude both in meters and in feet. In the US you are prefer the imperial units same as aviation world. But most of people refer to the International System of units.
      Then 800h is a short cut for 800hPa. The atmospheric pressure is used by meteorologists for levels.
    2. This curve is the pressure asl and corresponds to the figures above 1019, 1012 (hPa)
    3. It is strange that your Meteogram shows no cloud, as there are cloud icons in first line and cloud base at bottom line. Is it always like that?


  • @idefix37,

    Thanks for the response.

    1. Yes, different parts of the world use different units, but we have a choice in the Settings for what we’d like to see. Given space is at a premium on mobile devices, it seems that both might not be necessary. Not a big deal.

    2. I understand what the curve is and the pressure labels at the top. My second question was about what FL100 means.

    3. It is not that there is never any cloud show, but just that it isn’t always shown in cases where I would think it would be. Here is another example that shows the clouds in some cases:

    8fee8e23-528f-4b60-8825-e4a6817c345a-image.png

    My question is why are clouds not shown at (say) 9 PM Tuesday. The icon on the second row shows it being partly cloudy. The bottom row shows the cloud base at 28k. Is that too high to display on the meteogram? Although it is not labeled, it look like the top row of the cloud graph might be around 13K. Or does everything above 9km just get stuck there?


  • Sailor

    @btschumy
    FL100 is a short cut for Flight Level 10000ft. So FL300 (or 30000ft) you should have clouds if their base is 28000ft.
    Have you tried to see what the Clouds and High clouds layers shows near your location at same time?



  • Yes, I have looked at the cloud layers. At 9 PM, it is showing 35% high clouds and 23% medium clouds. That was why I was surprised to not see them in the meteogram.



  • @btschumy The cloud layers and Meteogram are not synchronised. In Meteogram we are using some different calculation. Cloud maps are based on ECMWF data.



  • That’s too bad although it seems to be a common issue in weather apps. Different displays are not synchronized with each other or are using slightly different calculations. However, I can live with it as long as I understand what is happening.

    In your opinion, which is to be most trusted? The meteogram or the map layer?



  • @btschumy
    IMO, the map layer.
    The, so called, clouds in meteogram depict areas of high relative humidity.
    And, even in areas with R.H. 95% you may have no clouds.


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