Recently in play, the question came up of when does it get dark?
I had to make up something.
It happened to be early summer in the game, so I could use the approximate times from this time of year.
However, time progresses quickly in the game, so it is now mid-Autumn, so there is less daylight. When the players are running around outside, the amount of light tends to be important. Rather than make something up on the fly and it be radically inconsistent with past rulings, I built a chart for use at the game table.
I have put together a sunrise/sunset and hours of daylight for each day on my game calendar – Calendar And Random Generation.
I use twelve months with twenty-eight days for simplicity of generating random date. This is a game, so it does no have to have total verisimilitude with reality, just enough to make sense.
Google is your friend for esoteric information, but I wanted a chart I could print out for the game table and have ready without having to have my tablet or laptop available.
I picked a location that was in a temperate zone analogous to the current area in use in my campaign. I looked for sunrise and sunset times for Spring and Autumnal Equinoxes and Winter and Summer Solstices. I then determined how many days were between each and the difference in times between each and determined the number of seconds sunrise and sunset was earlier or later depending on the season. In reality, there is not exactly 59 seconds earlier sunrise each day, but again, this isn’t reality.
Of course, closer to the poles have more light certain times of year. I don’t know the formula but each degree of latitude N/S is approximately 69 miles for an Earth-sized planet. You can add or subtract minutes to the rise and set times based on the formula. I am sure Google has it. Based on Sturgis, MI and Kansas City, MO being about 2.7 degrees apart, the Spring Equinox sunrise time in Kansas City, MO is about 24 minutes earlier than Sturgis, MI. Sunset the same day is thus also earlier in KC. It is close enough to a 24 minute difference on the Autumnal Equinox and the Solstices, that one can extrapolate about an 8 minute difference for every 69 miles north or south. If you want to get fancier with your own calculations that’s cool. If you want a table for a world that is messier and more like reality, that’s your choice. I made the choice to spend as little time on this as possible at the table.
I have shared a PDF of my efforts – Sunrise & Sunset Times.