Alexander Leidinger

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Sep
02

What to do with the weather data?

As can be read in the pre­vi­ous blog post­ing, I have now some weather data around. Here the header from the CSV file I gen­er­ate out of the XML file of the soft­ware:

Date;Humidity (room);Temp (room);Humidity (out);Temp (out);Pressure (abs);Wind (ave);Wind (gust);Wind (dir);Rain

Cur­rently I pro­grammed the weather sta­tion to save the data every 5 min­utes. The long-term goal is to decide if a given wind tur­bine deliv­ers a sane amount of energy (dur­ing a com­plete year) at a given place. As I do not want to wait that long to get some infor­ma­tion out of this, the ques­tion arises, what I can do with this weather data?

Here an exam­ple of the out­put (ignore the rain and wind val­ues, the sen­sors are not attached at a place where there is wind or rain, the com­plete set is hor­i­zon­tally on the floor instead of ver­ti­cally how they are sup­posed to be; and do not be shocked about the room  val­ues, it is the “server room” in the basement):

2010-09-02 12:55:01;52.0;18.700;30.0;27.000;978.600;0.0;0.0;135.0;4.200
2010-09-02 12:50:01;53.0;18.700;30.0;27.500;978.600;0.0;0.0;135.0;4.200
2010-09-02 12:45:01;53.0;18.600;30.0;27.300;978.500;0.0;0.0;135.0;4.200
2010-09-02 12:40:01;53.0;18.600;30.0;27.800;978.600;0.0;0.0;135.0;4.200
2010-09-02 12:35:01;53.0;18.600;30.0;27.700;978.500;0.0;0.0;135.0;4.200
2010-09-02 12:30:01;54.0;18.500;31.0;27.500;978.700;0.0;0.0;135.0;4.200

Some things I came up with myself:

  • A line-graph of the val­ues dur­ing a day/week/month.
  • A graph of the amount of accu­mu­lated rain per hour/day/week/month/year.
  • The aver­age temperature/humidity (as an error bar, so see the min/max too) per day and night, but what to use as the times where the day starts/ends? I would like to have the day-part cover the real day­light time (minus some ramp-up and ramp-down time), but I do not have any idea how to get this for each day and for my region.Does it make sense to do the same per hour (with­out any ramp-up/-down)?
  • Does the com­bi­na­tion of tem­per­a­ture and humid­ity and maybe wind tell some­thing? If yes, how to com­bine them and how to inter­pret the result?
  • Sim­i­lar for the pres­sure. I do not know what it tells me, but in a graph I can maybe add some hor­i­zon­tal lines which tell some­thing (rain prob­a­bil­ity and maybe dan­ger zones?).
  • For the wind speed the instruc­tion man­ual comes with a nice table of the beau­fort scale and a cor­re­spond­ing descrip­tion. This can be put into some col­ored hor­i­zon­tal lines which show more or less dan­ger­ous speeds.

For the plot­ting of the data, I intend to use gnu­plot with the CSV data as the input. It should allow me to auto­mate a lot of things, and some of the graphs should also be easy to real­ize inside gnu­plot itself with­out any exter­nal pro­cess­ing, the ques­tion is only how to real­ize it. For exam­ple for the aver­age of some val­ues I do not know if it makes sense to use some­thing else than the arith­metic mean.

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3 Responses to “What to do with the weather data?”

  1. Nicola Terry Says:

    Know­ing the wind speed you can use this to pre­dict your power out­put for a real tur­bine. Dif­fer­ent tur­bines are opti­mised for dif­fer­ent loca­tions — the cut in speeds and max­ing out speeds varies. Every wind tur­bine should have a power/wind speed curve. For exam­ple there are some here:
    http://westwindturbines.co.uk/products/10kwwindturbine.asp. You can feed in the curve data and inte­grate hourly for a good esti­mate. How­ever, gusti­ness will affect it too and I don’t know much about that. Also, obvi­ously you need to have mea­sured the wind speed where the tur­bine is going to be. Wind speed increases with height above the ground, usually.

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  2. Nicola Terry Says:

    Another thing you can do — you can work out your degree days and cor­re­late that with your home heat­ing con­sump­tion to see how well your house is per­form­ing insulation-wise. Degree days is the sum of (days * degrees C heat­ing need) over time. It allows you to mean­ing­fully com­pare your energy use from one week to the next when it isn’t the same tem­per­a­ture out­side. There is a good expla­na­tion of it here
    http://www.energylens.com/articles/degree-days

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  3. netchild Says:

    That is the rea­son why I bought the weather sta­tion. After a year of col­lect­ing data, I want to get the data sheets of inter­est­ing tur­bines and cal­cu­late the power output.

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