GMT -> BST — and some wind issues

Last Sunday, here in the UK, we turned our clocks forward an hour from GMT to BST. This was a bit of a significant event for my weather station setup because, when I first started work on the tools that would pull the data off it and present it on the website, I decided that local time (rather than Universal Time) would make more sense. For reasons I won't bore anyone with it was important that I selected one or the other as the primary method of dealing with time and given that weather data lends itself more to how we portion up our days local time was the choice that won.

There were a handful of minor problems, all of them were to do with presentation and, in each case, they were to do with the fact that I'd written some code that assumed UT rather than GMT/BST. As far as I can tell each of these issues is now dealt with and things are displaying correctly.

Of course, the real test will be the switch from BST to GMT. Skipping forward an hour is one thing, skipping backward an hour is quite different.

The last 24 hours or so has been very windy over the UK but you wouldn't really know it by looking at the data from my weather station. The maximum speed I've recorded in that time is 19.5mph — I'm pretty certain that we've had sustained speeds greater than that and we've easily had gusts over that.

I've read in a few places (including a comment someone placed here) that the vane/anemometer that comes with the WS3600 heavily under-reports wind speeds and this would appear to be the case.

Watching the vane yesterday I'm wondering of the problem all comes down to it using an impeller that has to be turned into the wind by the vane. Consider this graph of wind direction from the second half of yesterday:

I would have said that yesterday afternoon and late into the night had far stronger wind speeds than during the first half of the day. Notice how there is no clear direction in the image above? I noticed this while watching the vane, the stronger the wind the more it gets blown around, the less it faces into the wind. If it isn't facing into the wind the impeller isn't going to be getting the full force of the wind and will generally under-report the speed.

Without actually looking into this (something I've not done but will at some point) I'm guessing that a separate cup anemometer and vane setup is a better solution than an impeller attached to the vane.

To be fair, I've not got the vane placed in the most ideal location and this might also have something to do with what I'm seeing. While the vane is above all the nearest obstacles there's no useful way I can have it high enough that it's above the height of my house and the house next to me. It's not close to them, but I'm sure there's still plenty of turbulence off them. Again, in this sort of setup I'm guessing a separate cup anemometer would be a better choice.

File Under: GMT, BST, Daylight Saving, WS3600, Wind Speeds.


Got the bits

The bits I ordered a couple of days back have turned up. I just quickly stuck one of the propellers on the motor, wired it up to the solar panel and went outside while there was some sunlight about and.... it worked!

That's not to say it's going to solve my problem, but I could feel a breeze off the propeller so in the confined space of the shelter it might just make a difference.

I don't know when I'll get to actually work on this, and I need to figure out how best to hook it all up and how to site it in the shelter — and being the sort of person who knows very little about electrics and related matters it might take some time.

File Under: WS3600, Shelter, Temperature, Thermometer.


Toy fan

After this morning's apparent failure of the shelter to solve the temperature reading problem I got to thinking some more about how the problem can be solved. One option would be to have some sort of fan that would keep the air moving in the shelter — I don't know how well this would solve the problem but it's something that's got to be worth a try.

So, how to go about it? I guess the obvious solution would be a PC fan with a power supply and I'll probably look into that at some point. However, I've been looking for an excuse to order some fun things from MUTR so I had a quick look for some ideas on there. One little shopping trip later and I'm wondering how much fun can be had with a solar panel, a small motor, a polythene fan and a miniature impeller blade. I'll find out soon enough.

Heck, there's even a chance that mucking about with such toys will result in some sort of solution.

File Under: MUTR, WS3600, Solar Power.

First test of the shelter

Almost as soon as I comment that I've not had a test of the shelter yet the Sun comes out. It's quite cloudy out there and, even in the gaps, it's thin cloud, but there is sunlight falling on the shelter.

And, so far, it looks more of a failure than a success. As of the time of writing (around 09:13 local time) the temperature has gone up to 6.1°C from a starting point of around 4.5°C (and it appears to still be rising).

Looks like I'm back to the drawing board again. I guess the next stop is to look into the idea of turning the shelter into a fan aspirated shelter.

Oh well, at least the transmitter is protected from the elements...

File Under: WS3600, Shelter, Temperature, Thermometer.


Gimmie Shelter

Yesterday I finally got around to installing the shelter and moving the thermometer (which is also the hygrometer and transmitter) into it.

It wasn't such a difficult job either — took just under an hour. To be on the safe side I disabled the downloading of data from the base station while I did the work (you can see the gap in the data here). I did this because I was going to be handling the thermometer and also unplugging the anemometer and the rain bucket — given that no data would be coming from them there was a chance that odd values could have been recorded. The only error to come out of the exercise (so far anyway) was a record of 0.5mm of rain; chances are I nudged the rain-bucket while getting the ladder in place and this would have caused a tilt.

So far, so good. One concern was that putting the thermometer in the shelter would mean that it didn't record lower temperatures so well but the values recorded over night look pretty much okay. Right now the external temperature is showing as 0.9°C — exactly the same as the little Maplin internal/external thermometer is showing. My nearest personal weather station is currently showing 0.4°C.

The real test will be what happens when it's sunny and sunshine is falling on the shelter itself. It's totally overcast at the moment so it looks like I won't be able to test that today. Unsurprisingly the forecast for a large part of this week seems to be more of the same so I might have to wait a while to see if the shelter solves the problem.

File Under: Personal Weather Station, WS3600, Shelter.


CloudCam: The Movie

After this morning's problems the camera seemed to settle down a little bit. The image has been far too dark all day but most of the time you could see the clouds and the light levels of the images did seem to relate to the light levels outside.

So, now that I've got a whole load of jpeg files sat in a directory, what to do with them? Easy, take one copy of ffmpeg and make them into a movie!

Note that it's a .mov file and that it weighs in at around 2.2MB.

If I can get the camera to actually behave itself and if I get an interesting weather event happening this might be one interesting additional way of recording it.

File Under: Weather, Clouds, Sky Camera, Cloud Camera, WebCam, ffmpeg.

CloudCam problems

The first day of testing the camera more or less worked and, unsurprisingly, over night all that was shown was a black square. However, this morning, it's not worked very well at all.

Yesterday I initially started using a tool called streamer to grab the images from the camera. When I had it set up in the office, pointing in the office, it worked fine. However, when I had it looking out of the window I mostly got a blank, white image. I then added a delay (this can be supplied on the command line) to give the camera time to adjust its brightness levels and that more or less worked. But, even then, I'd get the occasional white-out image.

I then decided to have a look around and see if I could find a different command line based tool for grabbing an image. vgrabbj was my next choice. This appeared to work rather well and it produced good images without the need for a delay. It also seemed to be a better choice because it provides a method of adding a timestamp to the image itself.

This morning, from just after sunrise, it's also been producing mostly white-out images too. It also has a parameter that causes a delay in grabbing the image and so I've made use of that. Even then the camera still seems to be having problems adjusting to the light levels. Chances are the problem all comes down to it being an old camera.

I'll carry on playing with it for a short while longer but, at the moment, the current setup isn't looking too promising.

File Under: Weather, Clouds, Sky Camera, Cloud Camera, WebCam.



Today I dug out an old Creative VideoBlaster II web camera; the old sort that connects to the parallel port and takes power from the keyboard connection. I hooked it up to one of my GNU/Linux boxes and rebuilt the kernel to provide support for the camera.

So, for the moment anyway, my weather site now has "CloudCam".

It's simply sat on a windowsill, pointing out of the window at the sky. To be honest it's not a very good setup and the quality of the image is pretty terrible (to take an image I have to start it up and then wait 12 seconds before the balance has sorted itself out) but it's a fun thing to try out. In the long term, if it does work out okay, I might see about hooking up a better camera and sorting out a better position.

File Under: Weather, Clouds, Sky Camera, Cloud Camera, WebCam.


Another base station crash

Last Saturday I happened to pop into the office and, while in here, noticed that the base station had crashed again. This happened at around 14:32 and I revived things around 14:57. It would appear that the crashing of the WS3600 is going to be a pretty regular event.

So far, since the station went online on 2005-12-27 I've had the following problems:

I'm not seeing any sort of pattern in the above.

File Under: WS3600, Personal Weather Station, Base Station Crash, Base Station Reset.


Record low temperature

Between 05:00 and 05:30 this morning the weather station recorded the lowest temperature I've managed to record so far: -6.6°C.

I was actually out doing some observing at the time and it really did feel rather cold.

Sadly, despite the fact that as of the time of writing it's still around freezing out there, the station is recording 12.1°C due to sunlight warming up the thermometer. I'll be really glad to get the shelter finally finished and installed. Just one part of it needs a final coat of paint and then I can get it all set up.

File Under: WS3600, Record Temperature.