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Normal time and daylight saving time


There has been a poll in the EU about daylight saving time. Keep it or drop it? If we decide to drop it, what time zone do we use instead? Constant daylight saving time or constant normal time?

Roughly 1% of EU citizens took part in the poll. While it was a poll officially done by the EU, it’s not comparable to an election and it won’t necessarily dictate what’s going to happen. The EU guys just wanted to know “what people think about it”. Well, there is indeed a lot of heated emotional discussion, but I will not chime in on that. Instead, let’s have a look at some objective data. Here’s a screenshot of my desktop:


Like many people do, I have a couple of bars at the top of the screen and at the bottom. In the top right corner, there is this little widget:


It shows the time of sunrise and sunset at my location. So, today, it was about 7:02 for sunrise and about 19:43 for sunset. The red dot indicates “now” and the thin grey line indicates when the sun will reach its highest point. There’s a small margin of error, because I use simplified formulae to calculate those times. I got them from this german page:

Still, those times match those of online services such as pretty good. Let’s say, it can be off by 3-5 minutes.

Back to the EU’s poll. I have used that same tool to plot the times of sunrise and sunset throughout the year – but I have disabled the automatic adjustment for the change from normal time to daylight saving time and back. In other words, we’ll pretend that it’s either normal time (UTC+1) for the entire year or daylight saving time (UTC+2) for the entire year.

I’ve used the “sun” widget of infofeld, libfaketime (alternatively, just add a strptime to infofeld), plus a little bit of shell + ImageMagick + GIMP.

Here’s what it looks like for UTC+1 in southwest Germany:


(The red dot is fixed at 12:00 o’clock.)

And that’s UTC+2:


For completeness, this is what’s currently happening – changing from UTC+1 to UTC+2 at the end of March and back to UTC+1 at the end of October:


I, personally, find these graphs a little easier to grasp than ones like this. Probably because a round clock-like image is rather familiar.