3 ms·

This is poor science, and very weak support for 'definitely'. I didn't watch this all the way through this time, but I do recall watching it back in 2017 when

by Jedd 6y ago

This is poor science, and very weak support for 'definitely'. I didn't watch this all the way through this time, but I do recall watching it back in 2017 when it was posted -- IIRC he did this experiment <sic>, asserting all variables were controlled for, but in a garage with leaky walls, on a poorly insulated floor, with no control test and only once, in one location. Consider that hurricanes don't form within 5 degrees (~ 550km) of the equator - which gives a good indicator of just how strong (or not) the Coriolis effect is.

emmelaich 6y ago
There has been experiments, published in Nature in the 60s that did confirm an effect. I personally know one of the authors. The tub they used was something like 60cm deep and 3 or 4m in diameter. I can pull up the reference if you like. It wasn't perfectly reproducible though; in classic fashion when they demonstrated for a local newspaper (Sydney Morning Herald) the water went the "wrong" way. I have given the url / details here in HN a few years back.
- Jedd 6y ago
  That it's not perfectly reproducible should be setting off alarm bells, even for people who would really like this effect to work at the scale of a few metres.
  - emmelaich 6y ago
    I'm not sure that any experiment is perfectly reproducible. Though I would be very surprised to see a hurricane going the wrong way at mid-latitudes! Anyway, we're in agreement that it is a thing, and we just need a big enough tub to demonstrate it, correct? The force is perfectly calculable, and we can compare that to the effect of, say, a breeze across the top. ps. the reference https://www.nature.com/articles/2071084a0 https://www.nature.com/articles/2071084a0 "Published: 01 September 1965 The Bath-Tub Vortex in the Southern Hemisphere LLOYD M. TREFETHEN, R. W. BILGER, P. T. FINK, R. E. LUXTON & R. I. TANNER pps. my earlier mention https://news.ycombinator.com/item?id=15122988 https://news.ycombinator.com/item?id=15122988 Nature volume 207, pages1084–1085(1965)"
    - Jedd 6y ago
      Yeah, I can't access that Nature link from 1965. AIUI the math is that the delta in acceleration across a 1m bathtub north-to-south would be 1x10-8 m/s/s due to Coriolis ... so your starting conditions would have to be at a level of perfection that I don't think anyone's achieved, certainly not some bloke in a drafty garage with a kiddy's wading pool one time. I accept that in theory that delta definitely exists, but I don't accept that it can be, has ever been, observed at the tiny scales of a few metres, let alone the 100mm (toilet flushes) that's typically asserted by the faithful. I accept that across dozens of kilometres we definitely do see this phenomenon as it generates consistent, hemisphere-dependent, large wind events (eg hurricanes) once you get a good way from the equator.
  - steerablesafe 6y ago
    It's probably reproducible in the sense that if you do it a 100 times you get a strong statistically significant effect. They were probably unlucky that day.
thatcat 6y ago
Hurricanes don't form near the equator due to the equatorial subduction zone.
- Jedd 6y ago
  Hmm, I hadn't heard this claim before. And searching for neutral questions like 'Why don't hurricanes form near the equator' reveals consistently Coriolis Effect explanations. Wikipedia's article on subduction makes no mention of weather events at all. Do you have any citations for your claim?
  - thatcat 6y ago
    My mistake, I was misremembering some things related to the the Inter Tropical Convergence Zone from geography class 10 years ago. As an aside, the ITCZ is a trigger for hurricanes when it moves too far from the equator. https://www.eoas.ubc.ca/courses/atsc113/sailing/met_concepts/09-met-winds/9e-hurricanes/ https://www.eoas.ubc.ca/courses/atsc113/sailing/met_concepts...
  - mattbk1 6y ago
    Perhaps something relating to this was meant? https://en.wikipedia.org/wiki/Thermohaline_circulation https://en.wikipedia.org/wiki/Thermohaline_circulation

by Jedd 6y ago

emmelaich 6y ago

There has been experiments, published in Nature in the 60s that did confirm an effect. I personally know one of the authors. The tub they used was something like 60cm deep and 3 or 4m in diameter. I can pull up the reference if you like. It wasn't perfectly reproducible though; in classic fashion when they demonstrated for a local newspaper (Sydney Morning Herald) the water went the "wrong" way. I have given the url / details here in HN a few years back.

Jedd 6y ago
That it's not perfectly reproducible should be setting off alarm bells, even for people who would really like this effect to work at the scale of a few metres.
- emmelaich 6y ago
  I'm not sure that any experiment is perfectly reproducible. Though I would be very surprised to see a hurricane going the wrong way at mid-latitudes! Anyway, we're in agreement that it is a thing, and we just need a big enough tub to demonstrate it, correct? The force is perfectly calculable, and we can compare that to the effect of, say, a breeze across the top. ps. the reference https://www.nature.com/articles/2071084a0 https://www.nature.com/articles/2071084a0 "Published: 01 September 1965 The Bath-Tub Vortex in the Southern Hemisphere LLOYD M. TREFETHEN, R. W. BILGER, P. T. FINK, R. E. LUXTON & R. I. TANNER pps. my earlier mention https://news.ycombinator.com/item?id=15122988 https://news.ycombinator.com/item?id=15122988 Nature volume 207, pages1084–1085(1965)"
  - Jedd 6y ago
    Yeah, I can't access that Nature link from 1965. AIUI the math is that the delta in acceleration across a 1m bathtub north-to-south would be 1x10-8 m/s/s due to Coriolis ... so your starting conditions would have to be at a level of perfection that I don't think anyone's achieved, certainly not some bloke in a drafty garage with a kiddy's wading pool one time. I accept that in theory that delta definitely exists, but I don't accept that it can be, has ever been, observed at the tiny scales of a few metres, let alone the 100mm (toilet flushes) that's typically asserted by the faithful. I accept that across dozens of kilometres we definitely do see this phenomenon as it generates consistent, hemisphere-dependent, large wind events (eg hurricanes) once you get a good way from the equator.
- steerablesafe 6y ago
  It's probably reproducible in the sense that if you do it a 100 times you get a strong statistically significant effect. They were probably unlucky that day.

thatcat 6y ago

Hurricanes don't form near the equator due to the equatorial subduction zone.

Jedd 6y ago
Hmm, I hadn't heard this claim before. And searching for neutral questions like 'Why don't hurricanes form near the equator' reveals consistently Coriolis Effect explanations. Wikipedia's article on subduction makes no mention of weather events at all. Do you have any citations for your claim?
- thatcat 6y ago
  My mistake, I was misremembering some things related to the the Inter Tropical Convergence Zone from geography class 10 years ago. As an aside, the ITCZ is a trigger for hurricanes when it moves too far from the equator. https://www.eoas.ubc.ca/courses/atsc113/sailing/met_concepts/09-met-winds/9e-hurricanes/ https://www.eoas.ubc.ca/courses/atsc113/sailing/met_concepts...
- mattbk1 6y ago
  Perhaps something relating to this was meant? https://en.wikipedia.org/wiki/Thermohaline_circulation https://en.wikipedia.org/wiki/Thermohaline_circulation