Centretown Observatory:

2011-12-31

As you can see, live data collection and analysis have been suspended since December 16. We're now working to get things back online.

We deciced to stop the process when the number-crunching software started dividing by zero; most likely there's something funny in the wind- chill or humidex calculations.

The CTO Weather Webcam is back online. The server itself is now handling the job--our Chief Developer is becoming pretty competent at Linux system administration amd figured out how to make it work on our ancient laptop / net/webserver--making this now just a two-computer venture.

Live weather-graphics capture of mirrored graphics was restored about a week ago.

While we have debugging to do in the software, we're doing a major rewrite of the data engine, per the development roadmap. Also, all external data capture will now happen externally to the main program. XML data from Environment Canada, for example, will have to be processed by an outboard program that spits out data in a standardized format for the main program. This uncouples the system from any one hard-wired data source and opens up the range of sources to anything that can be captured to an ASCII text file.

We're cleaning up some ugly bugs where 'official' readings (daily highs and lows, for example) don't quite 'take', and cleaning up the stats- calculating routines.

There are other priorities right now, so the work will go on a little at a time. The system ought to be generating test output in a week or two and operational again by mid-month.

-Bill

2011-11-02

We've added a couple of graphics to display Earth's terminator from viewpoints directly above Ottawa, Ontario, Canada (home of the Centretown Observatory) and Tashkent, Uzbekistan. (Just because I like the way it rolls off the tongue.) As with all of the borrowed graphics here at CTO, you can click through to the source website for more information. Hint, hint. (While we would like to be your first stop for weather information, we'd really love to be your first of several stops.)

The 'terminator' is the boundary between day and night and runs in a circle around the world. At every point along the terminator, it is either sunrise or sunset.

I find a terminator map can give me a better sense of 'how long' until sunrise or sunset than checking on Sol itself. Likewise for the progress of the current season. Because glancing out the window in these-here parts can be uninformative from November through March. You get the drift. We sure do.

Bazinga.

Here's something to watch for.

At the equinoxes, when spring and autumn begin, Earth's axial tilt is 'sideways' or Equator-on to Sol; the terminator therefore runs straight North-to-South, and so night and day are the same length, everywhere on Earth.

At the summer solstice, our hemisphere is tilted 23 degrees sunward and away from the dark. The terminator runs from the Arctic Circle to the Antarctic. It's high Noon at the North Pole and Midnight at the South.

If you take a quick peek at those terminator graphics every few days, you'll soon notice the changing angle of the termninator, especially if you tune-in around sunrise or sunset, ET or UZT.

By the way, if you open either graphic in a new tab, you can change the image size, and the latitude and longitude of the center point, very easily by editing the URL and refreshing. Perhaps you're not fond of Tashkent, or you just want to see the wealth of extra detail in a larger image.

I'll be back.

-Bill

2011-10-31

The (cheapo) CTO Weather Webcam is picking up a dark-orange skyglow tonight. Usually, even on cloudy nights, it's pretty much black with scattered noise. In fact, as the evening grows late, and more lights are turned off as folks turn in, the glow is fading.

It's Hallowe'en. Lots of extra outdoor lighting is compounding the usual light pollution, whereby in settled regions the night sky gets washed out by all of the wasted light escaping upwards from civilization.

Doubtless the only other evening of the year when so much light is cast skyward, at least here in North America, is Christmas.

Light pollution has, in just a couple of generations, deprived most of the 'developed' world of an important part of our heritage as human beings: the night sky, aglitter with myriad stars. I grew up in rural areas as a kid. I got to know the night sky and remain an avid amateur astronomer, here in leafy, light-polluted Centretown. I learned how to get my bearings, quickly, from the night sky. I marvelled at the complex tracery of the Milky Way. I followed the planets on their repeating treks acround the sky. I spent a lot of time outdoors, in the dark. Perhaps that explains a few things. But I digress.

If you live in a rural area (and chances are, you don't), the following taunts may not apply to you.

Chances are you've never seen the Milky Way, except perhaps while away 'cottaging.' Chances are you can't point to and name two stars among the few we can see from our urbanized habitats. Chances are, in fact, that you wouldn't identify a single star, and most likely not a single constellation other than the 'Big Dipper' (itself only part of an actual constellation). You've probably never glimpsed the "Andromeda Galaxy," a fuzzy patch that is an entire Galaxy, possibly bigger than our own Milky Way, 2.4-million light-years distant--and easily visible to the naked eye in a dark autumn sky.

Grampa would not be impressed.

Hey, I'm not complaining much about holiday lighting, although multiple weeks of Yuletide photonics seems excessive. But consider for one moment the amount of light we waste into the sky, 365.2422 nights a year. The price is large and not confined to sentimental memories of watching shooting stars from Grampa's backyard. Many birds, for example, navigate by the stars. Ottawa is smack on a major migratory pathway of Canada Geese. Honk if you're directionally challenged.

Light pollution, in fact, encompasses more than just the sky; it also affects right here on terra firma. If you've ever had to draw the curtains to block out an annoying streetlight, you've been affected by light pollution. If you've ever stepped outside to spot the meteor shower J.J. was talking about on the news, and seen diddly-squat, you've been affected by light pollution.

Now, think about how much it costs us, both individually and as taxpayers funding public services, to scatter all that stray light up into the night. Think about your hydro bill lately.

Yep. We're all affected by light pollution--right where it hurts the most.

Think about it. It's not tree-hugger stuff; it's simple economics.

-Bill

2011-10-22

You'll notice we've now added graphics for Southern Ontario weather watches and warnings, and marine warnings for the Great Lakes. Useful info, and on a regional scale.

2011-10-22

It's about two-and-a-quarter years since the Centretown Observatory first went online with live weather observations. It's about two months since we got back online, with borrowed data; and, with any kind of luck, within a couple of weeks we'll have live local data running again.

It's been a bit of a haul, from there to here.

Two years ago, I bought a home weather station. I've been a meteorology nut since about age twelve; for years, in my teens, I'd dutifully recorded the daily high and low temperatures, measured the precipitation, worked up basic statistics. I dropped that as I reached adulthood but had always wanted to resume. In 2001, I got a digital recording thermometer and starting taking local readings again. It was interesting, running comparisons against the Environment Canada readings down at the airport.

Back to the home weather station. I was thrilled to be able to connect it to my PC and log realtime weather data, even post it to a website along with graphs, charts, and such; I'd always wanted to do that.

The thing worked properly for a couple of months and then went haywire, just after the warranty expired. The simple little CTO website went dormant, and I went on to deal with other things in life.

This past summer, I picked up a much-simpler home weather station. No wind data, no rain gauge, no PC connection. But This got me to hankering to get back online with weather data. I decided to 'borrow' Environment Canada's readings and amalgamate them with graphics from various sources, for a sort of local-weather portal page. Statistics would be useful, too. And, while I was at it, perhaps I could find a way to capture data from that cheapo home weather station, into my PC, interface or not.

I rolled up my sleeves and started coding.

Environment Canada (hereinafter known as 'EC') publishes hourly observations for various cities, in XML format. Using my Linux box (I just find it easier to develop for Linux), it was easy enough to put together a little bash script to download the XML file every now and then. Then, using Lazarus/Free Pascal, I wrote a program to read the XML file, extract the pertinent data, and store it in a data file. From there, it evolved to generate statistics. I added options to import bulk historical data and 'manual' corrections or official values. The dataset quickly grew.

Now, to get the data into web pages without a pile of javascript or database queries. Taking inspiration from Cumulus, I worked up a list of tags, to be embedded in a template page, replaced with the corresponding value during processing, and output to an HTML file. And, whaddya know--it works pretty well.

I resurrected the webcam. It's at least ten years old. I replaced it with my old Canon Powershot A80, using scripting and gphoto2 to capture images. It lasted about two weeks. Currently, I'm running a low-end retail webcam. It does the trick.

I wanted graphical aids, so I added a function to spit out formatted data for gnuplot to generate graphs and charts.

Back to the cheapo replacement home weather station--the one without any interfacing arrangements. I'd been thinking about it off-and-on while I worked on the data-capture and statistical programs, and I realized it did have a digital interface--the LCD screen. I wondered how hard it would be to set up a webcam-and-OCR arrangement. So, I set up the cam and the display in stable positions and took a few shots. I came up with a solution pretty quick. Each digit on the display is composed of two relatively-square cells. These cells appear in the same position in each webcam image. So, simply define the center point of each cell, and then scan up-down and left-right from that point, to determine whether the individual elements are activated. From that, you can figure out what symbol is being displayed. I threw some code together. With surprisingly little adjustment, it worked. At some point, I'll polish up that program, make it easier to work with, and release it.

So, here's what we've got going: