How much extra daylight per day?

Most of us are aware that from December 21st to June 20th, days get ever longer. From miserably short snippets of Winter sun, to the seemingly endless days of Summer our planet’s Northern hemisphere slowly tilts towards our Sun. I remember reading a book during a mid-summer trip up to the Isle of Skye which lies at 57.5° latitude, roughly as far North as Hudson’s Bay. It was almost midnight and I did not need any light other than the sun to be able to read. It’s very strange!

I love noticing that it is staying lighter until later in the evenings as spring advances, and this is accompanied by the return of migratory animals and the return to life of trees and flowers. It’s a lovely time of year that brings us hope and the sprouting of healthy food.

This got me thinking: we all love this extra daylight, but how much do we actually get from one day to the next? So I decided to pose this problem, as I really enjoyed solving it, and I intend to make full use of this bonus time from now until…

Using this graph ONLY, how many extra minutes of daylight do we get each day on average from the summer to the winter equinox, in Halifax?

Sun graph for Nova Scotia from www.timeanddate.com
graph showing daylight hours for Halifax, Nova Scotia, for 2019 from www.timeanddate.com.

HINT: I used Geogebra to get accurate measurements from which to perform my calculations.

Extra Questions

  • Do we gain the same number of minutes of daylight per day?
  • How does this situation change as we go from Summer to winter equinox?
  • Is this value the same at all places on planet Earth?
  • If not, where would it be greatest? Where least?
  • Why does the Ecuadorian tourist board describe Ecuador as: “The land of perpetual spring”?
  • What do the discontinuities in the graph show? (HINT: Your country may not do this!)

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