4 ms·
Not that it really matters, but the article also refers to it as “drawing water to the top”. That seems more representative of reality than “pumping water from
by cj 3mo ago
Not that it really matters, but the article also refers to it as “drawing water to the top”. That seems more representative of reality than “pumping water from the bottom”.
- margalabargala 3mo agoYeah it's the difference between creating low vs high pressure.
- card_zero 3mo agoThe low pressure is up there already, for free. Or the high pressure is down here, whichever way you want to look at it.
- chowells 3mo agoIf you think of it that way, you have a real problem. It only takes about 10 meters for the weight of a column of water to create enough downward force that it starts vaporizing, at which point no pumping action works. This is why any deep well has a submerged pump. You simply can't pull water upward further than that with negative pressure in the Earth's atmosphere. It must be pushed with positive pressure instead. This is why the question is interesting. You can't just suck water to the top of a 60 meter tree. There must be some kind of positive-pressure pumping involved.
- pulvinar 3mo agoThe trick for trees is capillaries, which change the equation. The 10 meter limit only applies to larger columns. With capillaries there's a high negative tension that allows evaporation from leaves to pull the xylem sap up 100 meters or more. There's no free lunch here. The Sun drives the evaporation, and if the tree were in a closed system with no solar input, the humidity would eventually get high enough to stop it.
- tenuousemphasis 3mo ago>if the tree were in a closed system with no solar input ... that would be the least of the tree's problems.
- deleted 3mo ago[deleted]
- theendisney 3mo agoThis line of reasoning has always cracked me up. The internal dialog acidentally out loud at the least flattering moment. I believe the correct response to be: The tree is a perpetual motion machine hooked up directly to the wheelworks of nature! It PUMPS 500 liters per day usibg Wind, solar, capilar action and evaporation! How do i charge my car with this?
- lazide 3mo agoWell, if you chop it down and burn it to boil water, then Use it to spin up a turbine…
- taneq 3mo agoIt’s like the pop sci fact that if you took all your blood vessels and laid them end to end… you would die.
- hinkley 3mo agoThis is still one of my all time favorites, although alveoli work the same way and are more fun to say. The other day my friend said they wanted a new nervous system and my brain went down this route of pulling out the old one and putting in the new one.
- theendisney 3mo agoI once coin the philosophical construct: the wireless p**s. The idea is to send the body to work while you stay at home and have fun. Is the new nervous system really you?
- deleted 3mo ago[deleted]
- kijin 3mo agoYeah, that "extreme low pressure" part of the article had me scratching my head. Even a complete vacuum at the top will not suck water up more than 10 meters! The author was probably oversimplifying for a lay audience.
- fc417fc802 3mo agoThat analysis only applies to a single discreet pump. A line of pumps in series does not suffer from that problem and that is roughly what a biological system would be expected to consist of.
- Sharlin 3mo agoThere are no pumps in a tree, in series or not. There’s nothing between the roots and leaves that actively drives water upward in any way. The xylem is literally dead tissue.
- fc417fc802 3mo agoPlease notice that the comment I was responding to there made claims of physical infeasibility that I was responding to. I was not expressing any claims regarding actual concrete trees that you could go and visit. More generally you seem to be dismissing out of hand the primary topic of discussion which is neither constructive nor enlightening.