I assume that many of you are as mesmerized as I by the
speed with which new information surfaces about Trump’s efforts to get foreign
rulers to dig up dirt on his 2020 rivals.
There have been endless comparisons to Watergate, but I lived through
Watergate, and for the most it was as riveting as the melting of a large pile
of snow in the Spring. This has more the
character of a volcanic eruption. It is
hard for us bloggers to write about it because in the time it takes for me to
tap out a comment on my keyboard new information will probably have surfaced on
CNN or MSNBC.
Rather than try to tame a whirlwind, I thought I would pose
two puzzles to which I would love solutions.
I am encouraged by the quality of the replies to my post on the vagaries
of senior moments.
Puzzle 1: Why do
clouds develop in discrete layers, sometimes three deep and ranging from 20,000
feet down to 1000 feet? Everyone who has
taken an airplane has noticed this, but I have no idea at all why it happens.
Puzzle 2: How does
friction work? For example, if I put on
a T shirt, it slides smoothly over my back and settles properly on my
torso. But if I have just taken a shower
and my back is still damp, it catches and bunches up and I must twist into
contortions to grab the hem and try to pull it down.
Surely these are well understood phenomena. Anybody have a clue?
8 comments:
I can't help at the moment, but Puzzle 2 reminds me of the Steven Wright joke, "If nothing ever sticks to TEFLON, how do they make TEFLON stick to the pan?"
While it's true that no blogger can keep up with the mainstream media in covering the current political situation, I for one prefer to hear your comments on said situation from your radical point of view as well as those from the point of view of the regular commenters on this blog, generally radicals themselves, than to get into question of popular science.
The fact that you may comment on a political situation half a day later than the mainstream media does does not in any way lessen the value of your comments in my eyes, since you have a unique alternative viewpoint that is always worth paying attention to and is much more worthy of trust than that of the mainstream liberal media.
Further respecting Puzzle 2, I'm going to guess that friction alone is not the culprit and that high absorbency, e.g., of cotton, contributes to the effect. How it contributes I don't know. Perhaps the fact that cotton is hyrdophilic and exhibit "capilllary action" explains why a cotton t-shirt buckles when it contacts water on skin. The cottom molecules attract, rather than repel the water, and the capillary action draws the water into the fiber.
Puzzle 2.
I think when there is water on your back both your skin and your shirt 'absorb' the water causing your shirt to cling to your back. So there exists a tug of war (or suction) between your skin and your clothing material for the water on your back. You could probably prove this is true by adding more water to your shirt or your back by standing in the shower while it is on. The more water the stronger the cling. Of course both your shirt and your back-skin will max out in absorption power. So you will not have a shirt or back with too much suction. This is probably the reasoning behind a wet-suit for scuba diving. Nobody ever ripped the skin off their back by removing a water clogged shirt.
Puzzle 2 con.
I believe there is no cling to a dry shirt on a dry back because both dry surfaces repel one another electrically. Probably wrong though on both counts.
For the cloud the best bet I have is that there is several physical mechanism behind the formation of clouds, and they can't happen at all heights at the same time, hence the layering of clouds.
For the shirt thing, the basic and quite incomplete answer is that the space between a wet shirt and the skin is mostly filled with a thin layer of liquid water, thus to move a wet shirt one has to fight against the quite high viscosity of water. This thin layer is formed because water is both attracted to the skin and the coton fibers.
The size of this layer is important, but without a picture, and some math, I will have trouble explaining why, but the core result is that the smaller it is the stronger will be the drag. With air instead of water the gap is bigger and the viscosity much lower thus the drag is much smaller and the shirt slides smoothly instead of sticking.
"The size of this layer is important" I meant thickness.
Wow, sounds good to me.
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