To Yak or not to Yak? And more physics in running.

Run date: February 2, 2010
Run time: Dusk.

To Yak or not to Yak?

That is, I suppose, the question that many runners ask themselves at the end of a hard fought race. But it is also the question I asked myself this evening before my run--not in reference to losing my oatmeal but in reference to whether to put YakTrax on my shoes for better traction in the light snow.

If the snow is more than about a half inch, YakTrax become beneficial as they keep your feet from sliding around. If you run with them on dry ground or a light dusting, they take away from your power and can become uncomfortable. Because I was running on campus, I figured most of the sidewalks would be clear from the heavy foot and bike traffic, and for the most part I was right.


View 2-2-2010 in a larger map

Some of the features of my surroundings I often notice while trekking through this weather are interesting snow formations. I picture the wind as a vector field flowing across the ground and around obstacles to distribute the loose powdery snow as a visualization of its movement. This is similar to the fun young kids (and old me) have dusting iron filings onto a bar magnet to visualize its magnetic field.

Today I noticed something curious, not for the first time, but for the first time I was able to stop and take a picture--along with a GPS tag of course! (Denoted on the map by blue tags) Most of the sidewalk on which I was running had a very light dusting of snow. This particular stretch has a wind tunnel that I feel every time I run down it, particularly on cold days. Most of the time, the snow has blown off the flat sidewalk. While passing sections of sidewalk next to trees, however, the snow remains at full depth. I don't quite understand how this happens, but the trees must somehow break the wind or redirect it away from the sidewalk below.

In the foreground of this image, you see the thin dusting that was characteristic of most of the sidewalk. Next to the trees, the wind patterns have changed enough that the snow doesn't blow off so easily.

Another thing I often notice in these weather conditions is the fact that underground tunnels--what I assume to be utility tunnels--become quite visible because the snow melts above them. This leaves a pathway of bare ground following the tunnel below. I didn't run past a great example tonight, but here is the best I could do, especially while losing daylight rapidly:


Usually, a manhole is a good hint, as it is in this case, but it's not necessary. Extending towards the background, you can see a bare stretch of land following the tunnel. There is a very nice example of this in the central part of campus--a large tunnel, but I wasn't running past it today. I have come up with a couple possible reasons for this.

1) The fact that the tunnel is filled with air doesn't allow heat to be extracted as quickly by the surrounding ground (convection vs conduction). It takes longer to cool the tunnel and the dirt above it to below freezing.
2) These are tunnels carrying small water pipes that are intentionally heated to prevent freezing. It takes longer to cool the dirt above the tunnel. They may be intentionally heated for a different reason, but this makes the most sense to me.

I think (1) would be most interesting. I don't know the actual cause, but if anyone has some insight, as always I'd love to hear it.

Created by My Tracks on Android.

Total Distance: 9.94 km (6.2 mi)
Total Time: 54:45
Moving Time: 51:16
Average Pace: 5.49 min/km (8.8 min/mi)
Average Moving Pace: 5.16 min/km (8.3 min/mi)
Min Pace: 3.03 min/km (4.9 min/mi)
Min Elevation: 211 m (692 ft)
Max Elevation: 252 m (826 ft)
Elevation Gain: 228 m (747 ft)
Max Grade: 5 %
Min Grade: -5 %
Recorded: Tue Feb 02 17:44:07 EDT 2010
Activity type: street running