Is podgraphing a word?

Tim Haynes, a friend and fellow geek that I've known for some years now, acquired a personal weather station not long after I got mine and he's also been setting his up and building a website based around the weather station.

This last weekend he knocked up something very silly but also lots of fun: a Weather Multimedia section for his site. Simply put, he's taking some of the data from his weather station and producing sound files from it.

File Under: Personal Weather Station, WS2300, Podgraphing, Sound Files.

Started work on the shelter

I've now started work on the shelter. So far, this afternoon, I've managed to build the main box and put most of the door together. It's turned out to be a little harder than I thought it might be. I'm the first to admit that I'm more than a little lacking in the DIY department (and I'm also one of those people who gets a little frustrated when things don't go together as easily or as well as I'd hoped) but this seems a little tricky — trickier than installing the weather station itself.

It's not that there's obviously anything wrong with the kit (not that I'm really in a position to know if there is), it's more a case of it being a job that often needs two pairs of hands and most of today I've only had the one pair.

The more it comes together the more concerned I am that it might not really do the job. The problem I've got is that the only wall I can mount things on faces east (ideally I should be mounting on a north-facing wall) and, obviously, the Sun in the morning causes me problems. I need something that's going to fully shade the thermometer during the morning.

Having seen the size of the gaps there are in the door (see right) I'm concerned that, during the morning, there might be times when the Sun is managing to shine right into the shelter and cause the problems I'm getting now.

I'm going to carry on with the build and installation no matter what (the install will probably happen in a week or so — once I've got the shelter built I still need to paint it and I generally only have the free time for this sort of thing at weekends). Even if this turns out not to be the perfect solution it should, at the very least, help protect the thermometer from the wind and rain. Also, if it doesn't fully work, the chances are that it gives me a base to build on.

File Under: Personal Weather Station, WS3600, Shelter, Thermometer Screen.

RSS feed and Google module

This morning I added two new facilities to me weather site. The first addition is a simple RSS feed of current conditions (if you've got a feed reader you'll find the feed over here). A sample of the current conditions is taken every ½ hour and added to the feed.

The second addition is a simple Google personalised homepage module. This gives a simple text display of the current conditions (the display is taken from here). If anyone wants to have a play you'll find the module here.

The latter seems to be all the rage today. It's nice to know that, where I lead, others follow. ;)

File Under: Personal Weather Station, WS3600, Google Homepage, RSS Feed.

A north wind from the south

For the first time since I added a "rolling average" plot to the wind direction graph we've had a wind from the north. This, as you'll see from the image to the right, has shown up a rather obvious problem with plotting a rolling average of wind direction. Because the wind direction oscillates around 0° I end up with an average plot that suggests that the wind is coming more from the south.

D'oh! (Yes, imagine me slapping my forehead in a "it's really obvious now I see it" way)

Mostly the average plot works really well and nicely shows where the wind is generally coming from so I'm left wondering how to correct this.

Now I can see why some of the more popular weather station software plots wind direction on a radar-a-like graph.

I've been meaning to see if I can do anything with the polar plotting facility in gnuplot — this would seem to be a good enough reason as any to have a play with it and see if I can produce something sensible.

File Under: WS3600, Plots, Charts, Graphs, Wind Direction.

Under the weather

Starting this weekend, I've ticked off another item on my weather station TODO list: I've started to submit data to Weather Underground. This means that my station has a page over there and you can also see it on the map of stations in my area.

Because I'm using Open3600 to pull data from the station I didn't have a tool to hand to do the submission (there is a tool that's part of the package — apparently inherited from Open2300 but it doesn't compile and seems to need a fair bit of work) so I decided to write my own submission program. I went looking for documentation but couldn't find any. However, there seems to be enough scripts around on the net to do this sort of thing that it was easy to see how WU accept the data — you simply supply it via an easy-to-construct URL. Half an hour of hacking away in ruby and I had a working tool.

I've set things up so that data is submitted once every five minutes — I figure that this strikes a nice balance between producing too much data and not producing enough.

The only outstanding jobs now are to see about constructing the shelter for the thermometer (which, I hope, will cure the temperature spikes I get when sunlight falls on it) and to find a better location for the rain bucket (it's currently in a bit of a rain shadow).

File Under: Weather Underground, Open3600, Open2300, ruby, Personal Weather Station.

Pressure corrected

This morning I finally got around to sorting out what to do about the pressure setting on the base station. I did some more searching on Google and found this thread on this BB.

Following the advice in there I adjusted the relative pressure setting in the base station's configuration menu, setting it to the current absolute pressure reading plus 1.25hPa and this seems to have put me pretty much in sync with other stations near me. It does, of course, mean that there's another large jump in the pressure data (you can see this from after 10:00 in this table) and that all previous data is "wrong". I might have a think about going back and fixing it at some point. That said, I did imagine that the first month or two of running the station would be a "play and see what happens" time so I'm not too worried about it. Given that I've still got to shade the thermometer and I need to site the rain gauge where it's not in a rain shadow I'm happy to take the view that this setup isn't fully "live" yet.

File Under: WS3600, Relative Pressure, Absolute Pressure.

Missing bits of shelter have arrived

The bits that I found were missing from the shelter arrived today so it looks like the only thing that's stopping me from getting it built and set up is free time.

File Under: Metcheck, Instrument Screen, Personal Weather Station.

Record of an occluded front?

I just noticed the jump in the outside temperature that you can see in the graph above. I'm used to seeing this, it's normally a sign that the Sun is out and sunlight is warming up the thermometer. Thing is, it's overcast at the moment so that couldn't be the cause.

I wondered what could be the cause of this "problem" for a short while and then decided to go on to the Met Office website to see if there was anything that could have been the cause of it. Looking at their charts I could see that an occluded front was due to pass over some time before noon. Armed with this information I headed off the Google to look up the term.

According to this page I should expect the following:

• Milder temperatures once it's passed. See the graph above.


• Pressure rise once it's passed. It's been rising slowly since around 06:00 today.


• A drop in the dew point once it's passed. It appears to have fallen behind the temperature in the last hour or two:
  
  


• Winds from south east/south before passing with a shift to the west after passing:
  
  
  Okay, that's more south west/south to west. But close enough?

Perhaps I'm way off here but it looks to me like I've just recorded my first identifiable weather phenomenon.

File Under: WS3600, Personal Weather Station, Occluded Front.

History now working

Further to the initial crack at getting a history section working, I did some more work on the site this morning and polished off the history section. Now data for any day can be viewed. The default is to view a hourly snapshot but other intervals, including viewing per-minute, are available.

Next job on the site is to include the rain data in the graphs and in the history.

File Under: Personal Weather Station, WS3600, Weather Website.

Shelter has arrived

The shelter I ordered last week arrived this morning. I've not had the chance to check all of the contents yet but, at first glance, it looks like it's more or less all there.

I say "more or less" — there's a note attached to the instructions saying that the instructions are from the 1980s and, since then, the wood they use has changed. Because of this it claims that the panel pins that are listed in the inventory are no longer included and that you should simply use a glue (they suggest No More Nails). Something else that's in the inventory but doesn't seem to be in the pack is the latch that holds the door shut. Hardly an expensive item to go out and buy but I'll drop Metcheck a line just to be sure.

Update: I just realised that the latch for the door isn't the only item that is missing — the hinge for the door is also missing. An email has been sent to Metcheck.

Update: Just had an email back from Metcheck. The latch and hinge will be going in the post tomorrow.

File Under: Metcheck, Instrument Screen, Personal Weather Station.

Screen on order

I've been meaning to sort out a screen for the thermometer/hygrometer for a couple of weeks now but, because the weather's been overcast most days for a while and the over-reading problem hasn't cropped up it sort of slipped down the TODO list.

Today's been quite a sunny day and the problem came back:

The hump you can see from around 11:00 onwards fits in exactly with the time that sunlight was falling directly on the unit.

So, finally, I've just been over to Metcheck and ordered one of their screens in kit-form (the M9 on this page).

Setting this up should be interesting. As I've said elsewhere before, I'm not a DIY sort of person so I don't have many skills in that department. However, I think (hope) I can handle banging some wood together and giving it a couple of coats of paint.

File Under: WS3600, Personal Weather Station, Metcheck, Thermometer Screen.

Feeling pressured

I'm confused — horribly confused.

I finally decided to get around to sorting out the relative pressure setting on the WS3600. I dug out an OS map of my area and checked my height above sea level (about 10 meters) and then, using this article to guide me, worked out what the relative pressure setting should be (around -1.25hPa based on that document if I'm reading it correctly).

So far so good.

According to the manual that comes with the station it says that I should subtract that value off 1013.0hPa in the "Relative Pressure" setting in the unit's configuration menu. So, I dived into that configuration item only to find that the value in there was something totally different. After a little head scratching I realised that the value I was seeing in there was the current relative pressure reading — not some sort of base value that I needed to fiddle with.

I made an attempt to adjust the value anyway (as you'll see starting from around here) and I think it's changed things in the right direction but it hasn't actually got it right yet.

As of the time of writing my station is showing an absolute pressure of 1019.9hPa and a relative pressure of 1011.2hPa. I've been wondering if it will suffice to simply set the relative pressure to 1019.9 - 1.25 (in other words: current absolute minus offset) — while that probably still wouldn't be spot on I get the impression it would be closer to correct. I've been looking at the values for stations near me (as of the time of writing: RAF Cranwell showing 1023hPa, Grantham showing 1022.3hPa and Branston showing 1022hPa) but I'm not sure if I should be reading those values as relative or absolute values. All are close to the absolute value I've got at the current time (and, of course, I'm close to sea level).

Like I said: I'm horribly confused now.

I think I've got some more reading and learning to be doing...

File Under: WS3600, Relative Pressure, Absolute Pressure.

Weather on my mobile phone

This morning I added a simple WAP page to my weather site — using this page (unless you've got some sort of WML browser plug-in for your web browser that link isn't going to work too well for you) I can now check in on the current conditions at my station from my mobile phone.

Not that it's that useful (most of my time is spent sat next to the station), it's more a case of "I can do it so I've done it".

File Under: Weather, WAP, WML.

More graphs

I've added another page of graphs to my site. In this case it's a set of graphs of the previous 7 days of collected data.

File Under: Personal Weather Station, WS3600, Weather Graphs.

Another effect of the strange reset

I think I've just noticed another effect of strange reset. When I sat down in the office this morning I noticed that, while the time on the WS3600 was correct, the date was showing as 2006-09-06 — a full eight months into the future.

Thankfully this doesn't seem to have affected the data I'm pulling off the base station. From what I can tell (I'll be checking the sources later) Open3600's logging utility writes the time stamp to the file based on the time on the machine running it, not based on the time on the base station. The only visible effect this has had is that some of the min/max values that are shown on the opening page of my site appeared to be in the future. I've reset the offending min/max values.

I had a look in the WS3600's manual this morning and, annoyingly, there doesn't seem to be any sort of "trouble shooting" section so I'm no wiser about the possible cause of the reset. Later on I'll do some searching on the net and see if I can find any more information.

Update: I just noticed that the minimum windchill recorded by the base station was on 2006-01-06 at 00:33. This is a long time after the odd reset. This would suggest that the date went out of sync a long time after the reset. Now I'm really confused.

File Under: WS3600, WS3600 Reset, WS3600 Incorrect Date, Personal Weather Station.

A strange reset

Just a moment ago the WS3600 base unit gave a loud beep, turned on its light, turned on every part of the LCD and then appeared to reset itself. Now that it's come back it seems to have lost all of its min/max records and the pressure history but, oddly, has retained the rain total.

I've no idea what caused that.

Yet another thing to keep an eye on.

File Under: WS3600, Personal Weather Station, Strange Reset.

Historical interest

I've done a little bit of work on the website to start an interface for viewing the actual data that I capture from the WS3600. You can see an example over here. It still needs some work — an interface for navigating to specific dates being the obvious requirement. It will take a parameter that is the date you want to view. An example of this would be viewing the data for New Year's Eve last year.

Having now written the code to do this I'm starting to wonder if capturing the data once every minute is a little excessive. While I do intend to add a facility that will summarise data for a day, week or month (giving a useful view without having to look at the raw data) I still have a feeling that making a record of the values this frequently gains little.

I'll have to have a look around some other sites that contain such data and see what they do.

File Under: WS3600, Weather Website, Personal Weather Station.