I just did my third night climb in the last week and a half. The days are too short now and my favorite climbing time in the evening is now well past sunset. I'm finding out that night is a great time to climb during cold weather. Generally at night the wind calms down and the cold settles near the ground. During my climb I took off my gloves in the tree and didn't need to put them back on. Once I was back on the ground it felt much colder. Even though climbing heats you up the air temperature feels warmer 40 ft. above the ground. Even the tree had warm spots on the trunk and branches. I don't know if it was retaining heat from the day but in many places it was comfortable to hold on with bare hands even though everything is frozen solid. There is snow cover on the ground now and it helps to light things up at night. So I encourage any of you cold weather climbers to try a night climb, it's pretty nice up there!
-moss

Sounds great! Thanks for this--it indeed encourages me to do such a climb.

Where did you do it? I'm interested in any problems with logistics (just getting to the location, etc.). For me, I can't think of a suitable place to do a night climb other than in my back yard, which really is not very exciting at all.

Thanks again, moss--it really was good for me to read your post.

I have two backyard tree options for night climbing, one is endlessly challenging (honey locust). The other one I have to manufacture challenges, it's a red oak. I've also been climbing at other urban night sites which I bicycle to. For a big fir I had to do rope placement at sunset, it was too difficult to throw in the dark on that one. There are two other trees, a sycamore and a european beech which are relatively easy to throw into in the dark, especially with snow on the ground. I leave tag lines in the backyard trees so I don't freak out my neighbors with throwbags going bump in the night. So far the most challenging thing is positioning my House cambium savers. I use them for every TIP except short back-up tie-ins in the canopy. Last night I had to climb up high enough so I could see if I actually had the pipe over the branch. When I saw that it was only half in I set a second TIP and re-positioned it.

I'll have to admit that my off-site climbs are ninja, that is I'd be shouted out of the tree by an officer with megaphone if I tried to do it during the day. These trees are not high profile location but are in areas where there is enough foot traffic during the day that a concerned citizen would probably drop a dime on me. Well that's another advantage of night climbing, it opens up the options. If people barely notice you in trees during the day they are definitely not going to see you at night.

PS:
It's wise to do tree assessment during the day for planned night climbs.
-moss

Hadn't thought about winter night climbing yet, but the days are indeed short enough that you considerably expand the possibilities. Right now I'm in the end-of-semester crunch and I haven't had time to climb for a couple of weeks. My only night climb was in the middle of the summer, and my rope was placed in the day. I'll probably stick with inspecting and throwing while there is light, but maybe just leaving a throwline up until climbing time.

No problem finding trees around here; I'm a short drive from Chippewa National Forest and several state forests. I can hardly wait to get into my favorite canopy-emergent pine trees on Star Island.

Incidentally, Moss, if you run across anything about branches being more fragile in the cold I'd like to hear about it. The arborists on the buzz board seem to be more worried about climber function than tree function in the winter, but there is enough uncertainty about the branch strength issue in my mind that I'm still seeking reassurance.

If I can get my tail out of bed soon enough I'd like to be in a snow-covered tree as the sun rises...

Originally posted by MarkF
...if you run across anything about branches being more fragile in the cold I'd like to hear about it. The arborists on the buzz board seem to be more worried about climber function than tree function in the winter, but there is enough uncertainty about the branch strength issue in my mind that I'm still seeking reassurance.

This has been discussed on the TCI board but there was no clear conclusion. As I remember the main points that came out were the following:

1. health and structural integrity of the tree is the most important factor regardless of the season
2. branches may be at their weakest in spring or early summer

We think of materials (_meta_ls, plastics) being more brittle in the cold but wood is a complex composite material that has evolved to bear weight, it doesn't follow the same physical rules. If branches broke purely from cold temperatures you'd see branches falling with no wind on extremely cold days. Winter limb failure is associated with heavy ice or wet snow loading and wind.

I guess there is a reason why trees drain their sap down for winter, having it freeze in the cambium could cause plenty of damage. There is nothing structural about sap so not having sap in the tree shouldn't make it less strong. It might make it more strong since there would be less total load on the tree. It would be interesting to know how much extra weight (sap and leaf mass) a hardwood tree holds in the canopy in the summer vs. winter. It might be that the tree is bearing less weight and is overall safer in the winter.
-moss

Moss wrote:
>It would be interesting to know how much
>extra weight (sap and leaf mass) a
>hardwood tree holds in the canopy in the
>summer vs. winter. It might be that the tree
>is bearing less weight and is overall safer in
>the winter.

OK, I couldn't resist having a stab at this one. I tried some back of the envelope calculations to get leaf mass for a medium-large deciduous tree (about 0.5 m diameter). It depends a lot on the exact numbers you feed in (sapwood thickness, leaf area/sapwood area ratio, specific leaf mass, fresh weight/dry weight) but I'm coming up with around 100 pounds of leaves for a tree that size using reasonable values. The other factor is the dry-down of twigs and branches associated with cold-hardening, and I haven't turned up the pieces needed to do that one, but the mass reduction is probably not any greater than that from loss of leaves, since the summer water content of twigs and branches is a good bit lower than softer tissues.

So you have a medium large tree shedding about the mass of a tree climber in the fall (not the same thing as shedding the mass of a tree climber as a result of a fall...). Not very much; the benefit of leaf loss for winter survival may be as much from the reduction of wind loading as from the actual mass loss. A good wet snow or hard ice storm can probably add a lot more mass than that in a few hours.