Shortest Day of the Year

It is currently 5 p.m. and still light outside. I know what most of you are thinking: this is not a big deal. Saying it's light at four in the afternoon is like saying the sky is up, and rain falls down. Those of you, however, haven't spent a winter in Alaska. 

Actually, according to The Old Farmers Almanac, we have 10 hours and 42 minutes of sunlight today. By March 21st, we'll be at 12 hours, just like everyone else. 

Our shortest day of the year is on December 21st, the winter solstice. On that day, we had 2 hours, 49 minutes of sunlight. My first year up here, over Christmas break, I sat and watched the sun come up, go across the sky, and touch down. My own records say 1 hour, 55 minutes. 

In the weeks leading up to the solstice, and in the couple after, I find myself getting grumpy.

 Two or three hours of light is just not enough, even with our freakishly long dawn and dusk time. I started taking pictures, because I just couldn't believe that people had decided to form towns up here. Here are some of the pictures out of my classroom:

This one was taken at 12:10 p.m. That's Angie's Portable on the right, and Laurie's on the left, for those interested, and a sign welcoming people to the playground in the front. This picture is facing due South, and that bright spot is the sun, thinking about coming up.

Here's a couple minutes later, we've finally, fifteen minutes after noon, reached a level of light so that we can see outside without turning porch lights on. But we leave them on anyway, because of what's coming: 

Yup, sunset. And what time was this picture taken? 2:48 p.m. There the sun goes, setting over the tank farm. (Burying  tanks of gasoline and oil in a ground that undergoes 100 degree  temperature variations is not the best idea. So the tanks live above ground.)

Lest you feel too sorry for me, please remember that in the summer-time, the opposite happens. Mostly. The sun sets around 1 a.m. and rises again around 3. However, because of the freakishly long dawn and dusk, it never actually gets dark for weeks in a row. 

Here is an interesting piece of information I found out while I was looking up actual sunrise times, from the Alaska Science Forum, May 10th, 1976: 

Shortest Day--Shortest Night

Article #66

by T. Neil Davis

This column is provided as a public service by the Geophysical Institute, University of Alaska Fairbanks, in cooperation with the UAF research community. T. Neil Davis is a seismologist at the institute.

Why, asks Mr. Jim Schneider of KUAC, is the shortest day longer than the shortest night?

Looking over sunrise-sunset times, he noticed that the shortest night (June 21) at Fairbanks is only 2 hours, 11 minutes long, but the shortest day (December 21) is 3 hours, 42 minutes.

Were it not for refraction of the suns's rays in the atmosphere, the shortest day would equal the shortest night at a particular latitude. Atmospheric refraction bends the rays so that they can pass over the horizon. Hence, the sun appears to rise before it actually reaches the horizon and it is still visible at night after it is actually below the horizon. Consequently, every day is longer than it would be if there were no refraction.

Hopefully this clears up any questions anyone has been having, and allows me to post some pictures while I was at it. 

For those of you who looked at those photos and thought to themselves, "That doesn't look so bad," I offer this: 

Remember that sign from the beginning of the post that welcomed people to the playground? That's it, sticking out of the snow behind that snow drift. The only reason we can see it is because the school is built up high enough to give us a view over the drift. And if you wonder where that snow drift goes, here is the rest of it:

These are not the best pictures, I took them with the laptop camera, and it's not getting the light right. I'll take more some other time. 

Thanks for listening. I hope you find this science stuff as interesting as I do.