Chart of the Day: Daily Incoming Solar Radiation (By Latitude)

You might have noticed that the days are getting shorter up here underneath the 49th Parallel (aka Canada’s Waistband). It’s not your imagination, it’s true! Insolation is a climatological term for Incoming Solar Radiation, or the total amount of the sun’s energy that strikes the Earth during a day. This number varies quite a lot depending on latitude and time of year.


arrow = now in Minnesota

For example, in Minnesota we’re at about 45º North, halfway between the red and green lines here. The point is that the number of hours of sunlight combined with the sun’s angle means our total amount of solar energy declines a lot, down to about 200 watts per square meter (WM-2) at the moment. That’s less than half our June peak, and a lot less than even a month ago. The total insolation drives our climate, so bring a warm jacket.

Bill Lindeke

About Bill Lindeke

Pronouns: he/him

Bill Lindeke has writing blogging about sidewalks and cities since 2005, ever since he read Jane Jacobs. He is a lecturer in Urban Studies at the University of Minnesota Geography Department, the Cityscape columnist at Minnpost, and has written multiple books on local urban history. He was born in Minneapolis, but has spent most of his time in St Paul. Check out Twitter @BillLindeke or on Facebook.