No, this post isn’t about wealth inequality. It’s about daylight inequality.
Today is the day of the spring equinox. For the past three months, the days have gradually been getting longer, and from tomorrow, the sun finally starts to spend more time above the horizon than below it*.
It’s also the day when everyone in the world enjoys a day of approximately equal duration. But from tomorrow onwards until the autumnal equinox in September, the further north you are, the longer your days will be, in the sense that the sun will spend more time above the horizon.
I wondered where Edinburgh, where I live, fits into this scale of day lengths. For the next six months, we’ll have longer days than anyone living south of us. What fraction of the world’s population is that?
I estimate that, over the coming summer, we’ll have longer days than roughly 99.3% of the world’s population.
I was very surprised at how large this number is. And delighted too: it somehow seems to make up for the seemingly endless dark dreich dampness of the Scottish winter.
Rather than counting the number of people who live south of Edinburgh, it’s easier to count the much smaller number who live further north.
There are a few countries that are wholly north of Edinburgh, namely Finland, Norway, Latvia, Estonia, Iceland, the Faroes, and Greenland. There are some countries that are partially north of Edinburgh: Sweden, Denmark, and Lithuania. And then there is Russia, which spans a vast range of latitudes, but which has relatively few cities north of Edinburgh, of which the largest and/or most well known are St Petersburg, Nishny Novgorod, Perm, Yekaterinburg, Tomsk, Archangelsk, and Murmansk (though I counted a few more). There’s one state of the USA: Alaska. Finally we have Aberdeen, Inverness, Dundee and Perth, the main centres of population further north in Scotland.
To roughly compensate for the fact that these counts don’t cover minor centres of population, and that the northern part of Moscow probably overlaps somewhat with Edinburgh, I included the whole of Sweden, Denmark and Lithuania in the sum, despite the fact that the countries have major towns that are south of Edinburgh.
When I added it all up, it came to just under 44 million people living north of Edinburgh, against a world population at the time (I actually did the sums a few years ago) of 6.8 billion. Expressed as a percentage, 99.35% of the world’s population live south of Edinburgh, which I’ll round to 99.3% to avoid overstating my case.
*Actually, the sun appears to be above the horizon even at times when, geometrically speaking, it is slightly below it. This is because the light rays are refracted by the atmosphere and so travel in slight curves rather than straight lines.