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Best graph yet! Sunrise and Sunset

7 12 2006

In honor of Swivel going live, I decided to undertake a project graphing the sunrise and sunset times in both Montreal and Saskatoon to compare them (I threw the equator in for fun too). I actually learned a few interesting things that I had never known before.



Although the real Montreal time is the yellow one, I also made up one (the red one) to show how we would be if we didn’t have DST. Here are the interesting things that I learned while poring over these graphs:

  1. Assuming that the equator and all time zones centered around the equator are ‘normal’ time zones and those that are off centered are some sort of saving time zone; Saskatoon is in a constant DST mode! You can see that it is not centered around the equator time (as is the non-DST Montreal time).
  2. The date when the sun changes from rising later to earlier (Jan 2nd) does not correspond exactly with the day the sunset changes from setting earlier to later (Dec 10th) which also does not correspond exactly with the date when the amount of sun time changes from being shorter to longer (Winter Solstice – Dec 22nd). Solstice is in the middle of the two other dates though so that makes sense. Same funny behavior at the Summer Solstice.
  3. I had just not thought about this one too much but I never understood exactly how DST works – this chart helped me to visualize it so I know what’s going on. So, in summer, DST lets us sleep one more dark hour in the morning and get an extra hour at night to play at the beach – fun!

OK, I think that’s all I learned for now. Source data for these graphs came from time and date.

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