The sun rose at 7:40 AM and will set at 6:13 PM. It may seem like we just crossed over into less than 11 hours of daylight last week but guess what, we're already down to 10 hours and 33 minutes. Those nearly three minutes less per day add up.
It isn't just the length of day that's cooling things down though. In addition to when the sun rises we need to look at how high the sun rises. The sun will rise to a height of 33.2°above the horizon today. Last Monday the sun reached a height of 35.7°. Back on the summer solstice, (at least here in the Twin Cities) the sun was 68.4° high at the highest point. The higher the sun, the more direct and less spread out the solar energy is. Even if we had the same hours of sunlight, we would still be colder if the sun was only at 30° rather than 70° high in the sky. It makes sense if you think about your practical experience with the sun. Which feels warmer, the sun high overhead or a sunrise? The sun is putting out the same energy in both situations but a sunrise feels cooler as the energy is spread out over a much wider area.
I know what you're wondering. How high does the sun get on the winter solstice? Only 21.6°. In a lot of areas, the tree line obscures 20° of the horizon so that means we barely see the sun barely. If you're north of the arctic circle, the sun actually doesn't rise at all on the winter solstice. I guess we should be happy with what little sun we do get.
Here's what I saw happening this past week.
Tennessee warbler 1
Wednesday we again had bird banding and the numbers paint an interesting picture that contrasts with the previous weeks. There were 51 total bird comprising 9 species. Both Ruby-crowned and Golden-crowned kinglets were around though in low numbers. They were joined by a measly 3 White-throated sparrows. They were the only migrants found that still need to head south. The "winter finches" that migrate to Minnesota were present in the form of 3 purple finches and 5 slate-colored juncos. There were also the resident chickadees, downy woodpeckers and white-breasted nuthatches.
Thursday I took the day of from work and decided to make a quick stop at Lake Como in St. Paul. It was hard to count but my best guess was over 400 Canada geese moving between the golf course and the lake itself. I looked but didn't see any cackling geese mixed in. There were two American coots as well. My car windows were covered in frost in the morning.
Friday morning I stepped out the back door and noticed a thin layer of ice on the surface of a large flower pot filed with water. On a human phenology note I've started to park my car in the garage for the night after I got tired of scraping frost off my car windows every morning. There was a beautiful sunrise but it looked like a winter sunrise. There were bands of pink and purple on what were likely old contrails. I saw bluebirds on way to work so they are still around. The freeze last night can't have helped their food situation. I also saw a migrating thrush of some kind but didn't get a good enough look to make an ID.
Saturday I worked and had the pleasure of being down at the lake with kids. It was a beautiful fall day. We were dip netting and the numbers of aquatic macroinvertebrates seemed to be lower than previous weeks. There were still plenty of dragonfly larva but fewer other insects such as water boatmen. We did manage to find a few water scorpions still. That was my last dip netting of the season. Hardy crickets were still jumping around on land by lunch time and an immature bald eagle did a nice fly over. Thirty or so crows, joined by jays and other birds were trying hard to mob something in the woods but we never did get a good look. White-throated sparrows were singing in the morning as well.
Sunday we got some much needed rain. I'm happy it wasn't snow. I'm not ready for snow.
The week ahead:
We're in the last week of October which means Halloween and Halloween always means freak snowstorms and costumes ruined by winter coats. Let's hope that isn't the case this year. Last Halloween was beautiful and I'm hoping for a repeat. The weather looks like it might hold out for us but then again, predicting weather more than a few hours in advance in October is kind of a joke. On October 28th, Jupiter will be at opposition which means it is exactly opposite the sun and also means it is out all night. Jupiter is also at perihelion which means it is closest it will be to Earth until the year 2023. All this week is a great time to observe the planet. Even with a pair of binoculars you can make out the four largest moons orbiting the gas giant. You can't miss it, Jupiter is the brightest object in the Eastern sky in the evening and Western sky in the morning.