
A Universal Law for the ‘Blood of the Earth’ - digital55
https://www.quantamagazine.org/a-universal-law-for-the-blood-of-the-earth-20181128/
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mc32
> At what angles do streams branch?

Do they mean merge? Streams tend to merge into larger (riverine) systems, or
am i reading this wrong?

Unless they are framing this from a downstream to upstream PoV... (which is
counter to the flow of liquid).

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Retric
It's framed from the downstream perspective.

However, this idea does not seem that rigorous. They are trying to fit a
pattern while ignoring the counter examples which is dangerous.

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mc32
Yeah but they’re hedging that by saying it is dependent on “rainfall”
characteristics of an area. But you’re right, it looks like they are trying to
forve their hypothesis on the environment despite inconsistencies and gaps.

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mirimir
I don't think that's "hedging". Indeed, they're arguing that observed
branching angles can distinguish wet climates (72 degrees) from dry climates
(maybe ~45 degrees).

> Also interesting are the exceptions. In arid places like New Mexico,
> networks branch narrowly, at around 45 degrees. That second angle “took me a
> long time of trying and failing” to explain by theory, Seybold said. They
> still haven’t solved the specific angle, but the team argues that in arid
> regions, occasional surface runoff carves steeper channels with narrower
> junctions.

> That then opened up a new possibility. If wet climate might brand river
> networks with the 72-degree signature of Laplacian growth, could that
> signature’s absence also reveal the existence of a different kind of
> climate?

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FlyMoreRockets
It doesn't rain often in New Mexico, but when it does rain, it is frequently
torrential, with flash flooding. Perhaps that has something to do with it.

