Wooster Hall at SUNY New Paltz has a neat feature:  the main staircase is aligned directly North/South, and skylights are positioned above it so that at solar noon on the equinoxes the bottom of the staircase is illuminated by four columns of light which crawl slowly across the floor.   It’s an exciting event on campus, for some reason.   This past spring I made a crude time-lapse video of this.   Also, on the summer solstice, and again at solar noon, the upper part of the staircase is illuminated.   I made a much better time-lapse video this time, which includes a demonstration of the reason for the change in the sun’s elevation, where I’m assisted by my 9-year old daughter, Amanda.

But what about the Winter Solstice?   There are no markings on the staircase or nearby, and in any case the sun is so low in the sky in winter that it’s not clear that there would be anything to see.   But since I’m always curious about such things, I decided I had to find out.

The weather for December 21st was expected to be overcast and rainy, so I actually visited Wooster hall earlier in the week, on two different days.  First, on Tuesday, December 18th, I was able to get the general idea of what’s going on:

As you can see, the four columns of light from the skylights move across the wall directly below the skylight,  but they don’t extend further down.

It seemed like I had gotten there a little bit late, so I came back earlier the following day.   This time I think I got the whole thing:

There is a jump at the very beginning of the video, where I repositioned the camera.  Unfortunately, I moved the camera closer to some lights on the wall, and it looks like that changed the contrast of the video and made everything darker.  Even so, you can see the whole event as the sun crosses over.

Both of these time-lapse videos were created using a very nice piece of software called TLDF  (which  stands for “Time-Lapse-De-Flicker).  Actually, I just used the free “lite” version for Mac, called TLDFLITE, and that worked fine for this project.   You can find out more about it at https://timelapsedeflicker.com/

One thing that’s very obvious from both videos is that there are not four full bars of light, the way there are at the summer solstice and the equinoxes.  There is a curved shadow that blocks the light, mainly on the left side, curving down to the right.  It’s probably something on the roof near the skylight, but I don’t quite know what.  I went to the top floor of the nearby Chemistry building to get a view of the roof of Wooster Hall, and I can see that there are ventilation stacks near the skylight which might explain the shadow, but I wasn’t sure either of them lined up quite right.

So now I want to get up on the roof to see what is in the way, and  to see if perhaps it can be moved out of the way.   If I can’t get up on the roof, then perhaps I can find someone with a drone to help inspect that area.  Stay tuned….