Sunday, 17 July 2011

Weather On-Line Part 2

Since April, when Carol gave me the Weather station, way too much of my time (and not to mention cash) has been spent on this new hobby and I haven't even got started yet. So far I have just mentioned that I got the station, now I will bore you with the details.

The most important part of the set-up is a Davis Vantage Pro 2. This consists of two major pieces, the ISS (Integrated sensor system) which contains most of the sensors and has to be mounted around 1.2m off the ground. It looks like this:

ISS, mounting & owner

The Console
 The console (shown left) gives you access to all of the data from the ISS (including some basic graphs)  keeps history and is where all the system set-up is managed.

The console is also where you plug in the data logger for connecting to the outside world (more on that later).

The ISS contains sensors for:
  • Temperature & Humidity (in the white thing underneath) and a powered transpiration unit (fan) to keep the air flowing around them. The power comes from the large set of solar cells on the right of the aspirator.
  • Rain (the big black thing which is the rain collector)
  • Solar & UV detectors (behind the rain detector, you can only see solar here)
  • Wind speed & direction (on the arm to the left of the post)
The console adds sensors for (inside) temperature and humidity.

On the front of the ISS there is a little white box where everything is connected together and then sent via wireless to the console and powered by the little set of solar cells on the front. Together that gives you a great standalone weather station.

Hello World
This is all very well if you want to keep yourself to yourself but this weather thing becomes much more fun if you get connected to the internet and onward to the rest of the world.

To do that you can plug a USB data logger into the console and connect it to a PC. The Davis WeatherLink software that came with the data logger was pretty crappy on the MAC so I got a copy of Lightsoft Weather Center which has a wonderful set of graphing tools and all the connections to the Internet Weather Networks you could want.

What is a Weather Network?
Weather networks allow you to provide your weather information to them so that anybody can gain access to your weather data. There are around 20 such networks around but most of them have some kind of local focus. Exceptionally the Weather Underground is global.

In the top right hand widget of this blog page you can see, updating every few seconds, data from my weather station via the Weather Underground (WUG) in almost real time! Now isn't that cool? More than that, if you go to my station on the Weather Underground website (try it by just clicking on the widget) you can look at historical data and statistics from the day the station went on line (around 4pm CET on the 30/4/2011).

WUG also uses sets of data from around the area to provide extended info, almanac's and forecasts. You can look at this here or just go to "current conditions" from my station's (IAGKINDH2) site.

Always on
So all that sounds pretty cool, so what is all this extra stuff that has been taking up my time during May, June and July? Well first up, was I didn't want to have my Mac on all the time to feed information into WUG. In theory I could have could switched it off and update less often, but that kind of defeats the object of real time don't you think? To fix this a clever German guy (Hi Boris) had already thought of this (and much much more) and produced a piece of linux based software (meteohub)  that can run on tiny headless PC's to handle all of your weather data requirements.  This sounded perfect and would run on one of the little Alix boxes which I had already experience with when building my firewall a couple of years ago.

After a few issues trying to get the software image on a CF card the Alix motherboard was put into a box, the CF card put in and the Alix booted up. I was pretty nervous about the changeover from LWC to meteohub but once the meteohub was set up and running the changeover went like clockwork. So what you see on WUG is being supplied by my very own 24x7 weather server since 5.6.2011.

Not enough wind (unusual for me)
As you can see from the ISS photos, the anemometer and wind direction sensors are mounted on the same pole. Given our shielded garden this was not good enough for accurate wind readings so the sensors had to go to the roof.

Of course, this is nowhere near the ISS so I had to either run a long cable across the garden or use a Davis wireless kit to have the wind sensors talk directly to the console, I went for the latter. So the 3m mast was delivered along with the wireless kit and I was ready to go.

Disaster, on my first explorations for an appropriate site I discovered the house was falling down (OK exaggeration) due to a split beam that should have been fixed nearly 4 years ago (when I was more interested in staying alive than anything else)! So in came the builders to fix that before the mast could go up.

The split beam
One advantage to this small disaster was that the builders were able to build me a mount for the mast on which the wind stuff was to be mounted saving me the trouble.

So on Saturday 7th July I got out my big scary ladder and with a bit of help from Joss and a few prayers to the patron saint of ladder climbers (St. Jacob, I think) up went the mast and my wind readings became official.

The next day out came the my little ladder to help me mount the wireless box. Unfortunately I didn't spend as much time stabilizing this ladder and forgot my prayers so while I was up putting in the last screw, the ladder decided to leave me hanging on the balcony to which the box was attached. I still have some of the bruises caused by the ladder which I had to land on because their was nowhere else for me to go.

Mast with Anemometer   
Wireless Box
No bones broken so I was able to stand back and admire my work and to check if everything was working. After a few days I could tell (and you can check too if you like) somewhat higher wind speeds and significantly more consistent wind directions.

So what else was there still to do?
Well, when I went over to meteohub  from LWC although WUG didn't lose any data (as the data logger was still on line to the console and recording until meteohub came online), meteohub itself didn't have any of the LWC data from the previous month and that was needed for other purposes (graphs, pc dashboards etc.

So after finding out the LWC and meteohub respective data formats with some help from Boris (Hi Boris) I set out to brush off my Perl skills (which apparently had gone down the drain) to get my lost data into meteohub. This is a work in progress as I keep finding myself some new weather maths to play with on the way.

So when that is finished I will be able to sit back and enjoy my weather station .....
or maybe not ......
here is stuff  on the to do list so far:
  • Getting my Meteohub  on the Web - so you too can look at all the fun I am having
  • Adding a weather (360 degree) CAM so I have records of cloud formations
  •  Before the winter sets in get my rain sensor heater so as I can measure water content of snow fall too (don't believe me?)
  • Virtual cloud sensor for meteohub to record cloud classifications (a whole subject on its own)
  • Lobby LWC to support meteohub (I do love their graphs)
  • Learn more about weather forecasting
That should keep me busy for a while.

 HINT: The cheap way to feed you interest in the weather:
  • Buy an i-Pad or use one that you have lying around
  • Download weather Pro-HD (CHF 6)
  • Enjoy

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