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Snow layer/landscape

Posted: Mon Dec 20, 2010 5:02 pm
by takibartek
Hello everyone,

My YoWindow location is Gdansk, Poland. For about 3 weeks we have had a constant snow layer varying from 2-15 cm I think. In other words the world outside is white :) I have no PWS station. As I have noticed, YoWindow shows the village with snow when the temparature is -5 deg C or below. For the most of recent time it was true for my location - outside there has been a decent layer of snow, and so showed YoWindow hence the temparature was also below -5 deg C. However on some rare cases when the temp rised to -3 or so the village was not covered by snow.

Now, what is my suggestion. Could you develop some "snow layer" alghoritm? I think YoWindow shall collect data regarding temperature and snow forecast. If it's possible YoWindow shall also retrieve weather data for previous 2-3 weeks. If there was snow falling AND the temperature over recent days didn't exceed 0 deg C, the snow layer should be visible. Then, some "snow melting alghoritm" should be implemented as well. Therefore, YoWindow shall aggregate the amount of snow that has fallen and estimate the snow layer thickness. Then, from this value YoWindow shall substract snow layer when the temperature was above 0 deg C. I don't know what's the relation between melting speed of 1 mm of snow and temperature, but I'm convinced that there must be some mathematical estimation for this. And going back to the idea, YoWindow shall compute when the snow layer disappears and when to turn off the snow layer in village landscape.

I think my proposal is clear, may be implemented and will be warmly welcomed by you, guys.

Re: Snow layer/landscape

Posted: Mon Dec 20, 2010 11:37 pm
by Robino
Further to takibartek's useful remarks, I would say that indeed the snow layer algorithm absolutely needs improvement. This the more that a winter landscape (with snow) is something very visual which needs to correspond with what you see outside, otherwise, Yowindow seems out of touch as a weather program, which you certainly would not want...
The passage from spring to summer, or from summer to autumn, or autumn to naked is not as dramatic visually, and therefore those passages do not need to be as correct as you would see outside... indeed where is the exact limit between automn and all the tree leaves having fallen off to a naked landscape: not so required to be precise on the day. But the passage to a white snowed landscape needs to be precise on the day!

Nowadays in Yowindow, a snowed landscape is only shown under 2 conditions, as I understand it:
1° when the season map indicates the winter period has begun (in the form e.g. 12.15:winter, when a snowed landscape should be shown starting dec 15), AND the temp is below +5°C,
or 2° when there is no winter period indication: when the temp is -5°C or below and it is snowing that day; when the next day the temp is e.g. -4°C, with still lots of snow outside: a naked landscape is shown instead... this is crazy.
These 2 conditions are very unrealistic unless applied to seasoned winter areas such as e.g. Siberia or St. Petersburg (Pasha ;-)... For the more on/off/on snowy areas in Western Europe/USA, the above algorithm is worthless...
I have noted that Pasha is already making all sorts of customer corrections as to when to start the winter in the season maps. I think even this goodwill from Pasha can not give satisfaction (where does it end?), and sooner or later another winter landscape mismatch with what you see outside will again occur.

I would therefore suggest the passage in and out of a winter landscape to be controlled entirely differently, and this in order to be much more realistic, in order to correspond with what you see outside.
Say, the max temp of a day is 0°C or below, AND weather reports indicate that it is snowing or will snow that day: winter landscape "on", and this for the following days also, as long as the max temp for those following days does not exceed 2°C (snow needs time to melt). This of course would require the program (or weather data) some kind of previous day temperature memory to be retained. But I think this is a problem, or is it?

Snow layer thickness to be displayed in their various degree levels is an entirely different ball game and hellish to implement as I would imagine. In my opinion, no real need to bother too much about that... First priority I think is to get it right as far as a visually correct snowy landscape is concerned... After all, that is what users of Yowindows expect from this otherwise wonderful program!
Go for it, Pasha!

Re: Snow layer/landscape

Posted: Tue Dec 21, 2010 2:19 am
by dc1jr
hi Robino,

I fully agree to your suggestion. Well based!

The future of YoWindow should be to work on this topic!!! The quality of the program is influenced by it.
Pasha, put all of your energy on it! This problem is discussed since February 2010 with no results.

kind regards


Re: Snow layer/landscape

Posted: Thu Dec 23, 2010 10:40 am
by par
Takibartek and Robinho, thanks for the algorithm suggestions.
Unfortunately weather history for the past several days is not provided inside YoWindow yet.
The algorithm proposed by Takibartek is exactly what we are going to do.
Actually this algorithm was proposed by a friend of mine 3 years ago :)

However, we need weather history access first.
No, sorry, first we need time for this task.
We care about this problem just like you do.
Please wait.
Stay tuned!

Re: Snow layer/landscape

Posted: Thu Dec 23, 2010 10:44 am
by par
I have added a couple of topics to our FAQ about winter detection algorithm and season-maps.

Re: Snow layer/landscape

Posted: Thu Dec 23, 2010 11:40 pm
by FvE
par wrote:I have added a couple of topics to our FAQ about winter detection algorithm and season-maps.
Great job Pasha,

Would you consider making this a sticky subject under Season maps please?