Told ya so. In I Feel a FAIL Coming On – Will Tuvalu Survive ‘Super moon’? Andi Cockroft pointed out that there was the usual media disaster hype, and the reality of what perigee moons actually do to affect tides, which isn’t much.
A “super-moon” will be a novelty for New Zealanders on Sunday, but for the 12,000 people of Tuvalu it is a foreboding practice for a future where rising seas make their homeland uninhabitable.
On Monday and Tuesday super-moon king tides will leave much of the capital atoll of Funafuti virtually below sea-level.
Source: http://www.stuff.co.nz/science/6858916/Super-moon-bad-news-for-Tuvalu
But the sea level/supermoon tide reality reported today sure didn’t match the hype earlier this week. In fact, it was a total predictive failure.
Source: http://www.nzherald.co.nz/world/news/article.cfm?c_id=2&objectid=10804057
FAIL with a cherry on it. .3 meter lower than tides in the spring that they weren’t hyping.
For why Tuvalu won’t succumb to sea level rise, read this: Floating Islands
And their own government doesn’t even believe the sea level alarm, because they are building new airports and resorts: Tuvalu and many other South Pacific Islands are not sinking, claims they are due to global warming driven sea level rise are opportunistic.
Follow the money. h/t to WUWT commenter “inversesquare“.
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I’m sorry Mr. Smith. Unfortunately those suffering from the Dunning-Kruger effect are always the last to realize it. Even when their lack of expertise is pointed out to them.
But the simple reality here is that you are in fact suffering from an overwhelming case of it. And in spite of your vast self-assumed expertise on the subject, the local village idiot in a typical fishing town or village who’s so thick headed he can’t hold a job, so the only way he can feed himself is to go down to the beach or tide flats twice a day at low tide, understands the tides better than you do.
Um, George, the two tides each day are not of the same height. ( I lived on a sail boat for a while…) I’m not going to argue the physics, just point out the existence proof. The wiki asserts this is due to the tide on the far side of the earth, from the moon, having less lunar gravity (inverse square law) acting on it. All I can say is “they are not equal” and there does look to be some theoretical reason for it.
https://en.wikipedia.org/wiki/Neap_tide#Range_variation:_springs_and_neaps
It looks like it may be due to the offset of the lunar position vs the equator (that changes on a 19 year cycle, IIRC)
I have no idea how this plays with the theoretical model. All I can do is point out that there is a difference in the two tides, the difference changes over time, and the difference seems to me to be related to the degree to which the lunar position is not aligned to the equator (as that changes on a multi year basis).
Essentially, the orbits of the moon and earth are not coplanar and the rotation of the earth is also out of kilter. This has effects. The two sides of the earth are at different distances from the moon, so have different total gravity impacts. That, too, has effects (though part of me wants to think they must be very very small). Sorting it out will take a physicist 😉 and not me. All I can do is point at it and say “Wha??”
@Dennis Cox:
I don’t know why, but some places only get one high and low tide per day. Unusual, yes, but they do exist.
From that tides wiki:
Tides are very complex beasts and the description of the calculation in the wiki is, er, not simple.
>>
E.M.Smith says:
May 8, 2012 at 8:39 am
Um, George, the two tides each day are not of the same height. ( I lived on a sail boat for a while…) I’m not going to argue the physics, just point out the existence proof.
<<
I wouldn’t throw George under the bus yet.
Let’s modify Newton’s gravitational law as follows:
F = Me*a = G*Me*Mm/r^2; where Me is the Earth’s mass, Mm is the Moon’s mass, r is the distance from the Earth to the Moon and G is Newton’s gravitational constant.
a = G*Mm/r^2
So let’s compute the acceleration due to the Moon’s gravity at three points: Earth side closest to the Moon, the center of the Earth, and the Earth side farthest from the Moon.
If we use Earth radius = 6371 km, Moon mass = 7.35E22 kg, Moon’s distance = 384,399 km, and G = 6.67E-17 N km^2/kg^2; then we get the following:
Near side = 3.432E-05 m/sec^2
Center = 3.319E-05 m/sec^2
Far side = 3.211E-05
If we set the center to zero and adjust the near and far terms we get:
1.13E-06 m /sec^2
-1.07E-06 m/sec^2
There’s only a 5% difference between those two values. But the area of the Earth facing the Moon is slightly smaller than the area not facing the Moon. If we calculate those areas using the following formula for spherical sector:
A = 2*pi*r*h
And adjust the values for this change–there’s only a 2% difference between the far side and the near side.
I imagine that if I went to full Calculus mode, the numbers would be closer still. I don’t have time to do the math at the moment.
Jim
Mr. Smith,
While the calculation of the tides may be a complex thing. The observation of them isn’t. One notable characteristic of the Dunning Kruger effect is that those suffering from it the worst are always in denial of the fact, including you. But when you’ve spent a few years actually living with the tides, and have some personal subjective observations to provide a valid foundation for your thinking, I might be willing to discuss this with you a little more.
In the mean time, if you want to fabricate a straw man argument that some places only have one tide a day based something you’ve read in a poorly written Wikipedia article, and your own assumption that the simple observation of the tides must be a complex thing, you’ll have to find someone else to pitch your argument to who’s as impressed with your self-assumed expertise on the subject as you are.
I’m not.
Diurnal tides (one per day, or more precisely 24h 50m) are well-attested, e.g. Fremantle, WA, which is clearly shown in the hourly tide record there, and an amphidrome; a point where there is no tide at all, though most of these points are very far from land, and I know of no coincident island with a tide gauge.
http://www.linz.govt.nz/hydro/tidal-info/tidal-intro/cause-nature
For general information. the highest spring tides occur at new Moon, when Sun & Moon are pulling in the same direction, and the highest perigee spring tides occur for a combination of perigee and NEW moon, not full moon as has just occurred.
MostlyHarmless Said:
Thank you. Please note that a new moon just happens to be one of the darkest nights of the month. So my simple subjective observation that the highest tides happen on the darkest nights isn’t such a stretch now, is it?.
My point in making that statement was simply to show that a Full moon at perigee is in fact not a BFD at all. But since it’s just another dark night if you don’t live close to the ocean, no one who lives inland ever notices a new moon at perigee, so no media hype from the scaremongers.
Diurnal tide predictions at Fremantle & Hillarys, WA here:
http://www.bom.gov.au/oceanography/tides/MAPS/wa.shtml
“””””Dennis Cox says:
May 8, 2012 at 10:25 am
Mr. Smith,
While the calculation of the tides may be a complex thing. The observation of them isn’t. One notable characteristic of the Dunning Kruger effect is that those suffering from it the worst are always in denial of the fact, including you. But when you’ve spent a few years actually living with the tides, and have some personal subjective observations to provide a valid foundation for your thinking, I might be willing to discuss this with you a little more.
In the mean time, if you want to fabricate a straw man argument that some places only have one tide a day based something you’ve read in a poorly written Wikipedia article, and your own assumption that the simple observation of the tides must be a complex thing, you’ll have to find someone else to pitch your argument to who’s as impressed with your self-assumed expertise on the subject as you are. “””””
Well nowhere in my posts did I ever assert there is just one tide per day, in fact I plainly indicated that the norm is two. And nowhere did I fabricate any strawman argument or anything else based on any wikipedia article, whether poorly written or scholarly; nor did I claim any expertise; just ordinary 4-H Club physics.
But the fact remains, that when the sun and moon are on the same side of the earth and its ocean as the observer (of the tide), with the moon in its normal position between the earth and the sun (for that geometry), it is most certainly daylight for that observer, who is clearly on the side of the earth from which the moon and the sun, are both pulling on the ocean bulge.
It is for you to explain why an observer on the opposite nightside of the earth; from which the moon and the sun, are clearly NOT pulling, the ocean bulge, why there is any tidal bulge at all. I don’t care whether your knowledge of why, comes from fishing observations or from 4-H club science; it is well known that there is (usually) a bulge on both sides of the earth, and moreso in the colinear geometry case.
Yes I know there are places that appear to have one tide daily, and places that appear to have none; all having to do with local anomalies that are fairly well understood for most such places. It was to eliminate those clear anomalies, that I simply proposed a simpler geometrical model for discussion, as anyone can clearly show that for that situation, that the two tidal bulges are the same, since the earth radius is a negligibly small fraction of the sun earth distance and the square of the ratio is even more negligible.
I’ll leave it as an exercise for the reader to calculate the expected values for that ideal case and then decide whether that difference in the two tides, would be discernable on any number of years of night time fishing excursions.
Maybe your fishing experience has been in locations that DO happen to have a higher night time tide from the associated day time one. Does that exclude all those other places where the exact opposite can occur. I know some pretty serious fisherfolk, who have fished extensively for years in virtually every place on earth that has catchable fishes; and I know they have experienced every imaginable tidal configuration, one could conceive of.
No I can’t say they have more fishing experience or tidal perception than you do; and I’m perfectly happy to believe that the preponderance of YOUR personal experience has been of higher night time tides. I do most of my fishing in places where tides are quite un-noticeable.
The difference between 3,000 feet of water and 3,005 feet of water doesn’t seem to be noticeable to me when floating on it, and when the fishes are in the top 40 feet or the water; they don’t seem to notice it either.
“”””” Jim Masterson says:
May 8, 2012 at 10:17 am
>>
E.M.Smith says:
May 8, 2012 at 8:39 am
Um, George, the two tides each day are not of the same height. ( I lived on a sail boat for a while…) I’m not going to argue the physics, just point out the existence proof.
<<
I wouldn’t throw George under the bus yet.
Let’s modify Newton’s gravitational law as follows:
F = Me*a = G*Me*Mm/r^2; where Me is the Earth’s mass, Mm is the Moon’s mass, r is the distance from the Earth to the Moon and G is Newton’s gravitational constant.
a = G*Mm/r^2 """""
Jim, your analysis indicates, and E.M.'s sailing experience suggests (to him) that the two diurnal tides are usually different; and your calculation of the moon's gravitational field for those three points indicates basically why, because the raatio of earth radius (idealized) to moon orbit radius (idealized) is significant.
So your quickie arithmetic shows that the usual greater tide, is with the moon on the observer side of the earth. So far so good; no argument from me.
But the assertion was that it makes a difference which side THE SUN IS ON, and Dennis asserts that the sun's enhancement of the tidal bulge is greatest (and evidently for him) noticeably so, when the sun is on the SAME side as the MOON; which clearly makes it day time for the observer.
Now you can do your quickie arithmetic again for the solar acceleration enhancement of the tides in the colinear geometry case, given the closest moon case, and figure out the delta in the total gravity for those three points FOR THE SUN BEING ON THE SAME OR OPPOSITE SIDE FROM THE OBSERVER, whether Dennis or E.M.
The original assertion was not which side of the earth (from the observer) the moon was, but whether the two colinear cases are different enough to be easily noticed by """"" the local village idiot in a typical fishing town or village who’s so thick headed he can’t hold a job, so the only way he can feed himself is to go down to the beach or tide flats twice a day at low tide. """"" or by me for that matter.
Lessee George Smith,
You’re right it was E.M Smith who brought up the one tide a day thing not you; so wrong Smith. And I’m not clear how it got plugged into a disagreement over a simple subjective observation about Perigee tides at new moon.
The statement that the sun and moon are on the same side of the Earth does not imply the location on Earth of that observer; only the phase of the Moon. When the Moon is on the same side of the Earth as the Sun, it is a ‘New’ Moon. And it is also the darkest night of the month.
And in fact the original simple subjective assertion was: “The highest tides happen on the darkest nights.” It’s still my standing assertion. Everything else you’ve piled on it to refute it is pure straw man argument, muddied up with a liberal dose of Dunning Kruger enhanced miscomprehension.
You also said:
Really? Are you really that thick? The are two tidal bulges, not just one. The fundamental error in your thinking is evident in your use of the singular, ‘bulge’. the proper word here should be ‘bulges’. Think plural. There may be locations on Earth where one or the other of them are not felt as much. But nevertheless, at any given time there always two tidal bulges in the world’s oceans on opposite sides of the Earth. And two high tide perspectives. One on each side of the world.
Whether you like it or not, and no matter whether it makes sense to you, there is no reason whatsoever to assume that a high tide observer must be on the same side of the world as the gravitational attraction that’s causing that tidal bulge. Because even though you find it confusing, and counter intuitive, at the very same time the Sun and Moon are pulling up a tidal bulge on one side of the world, another tidal bulge is facing away from the gravitational attraction of the Sun and Moon on the opposite, nighttime side of the world. The area of low tides is between them, not opposite them. So your statement that it is“most certainly daylight for that observer” is childishly naïve, and uniformed. It could just as easily be a nighttime tide he’s looking at. And it’s a pretty safe bet that if that observer describes that tide as being on one of the darkest nights of the year he wasn’t talking about a daytime tide.
But aside from that, why not just ad anal retentive to the Dunning Kruger thing. Because in point of fact you are way too desperate to make an anal retentive, nit picking mountain out of a mole hill.
And no, it is not for me to explain the physics of it all for you. It is also not for me to explain why the sun comes up. But it does.
Get yourself a tide chart for someplace on the coast. Compare the times, and heights of the tides to the phases of the moon from a good almanac. And also to your own assumptions and misconceptions. You never know. You might actually learn something.
>>
George E. Smith says:
May 8, 2012 at 4:41 pm
So your quickie arithmetic shows that the usual greater tide, is with the moon on the observer side of the earth. So far so good; no argument from me.
<<
I wasn’t trying to argue with you George. I think the tidal effect on both sides of an idealized body is the same–if it’s due to a single (idealized) point mass. I also think applying a little limit theory to this problem would demonstrate the mathematics (notice how fast the differences were decreasing in the two examples I presented). But as I said earlier, I don’t have the time at the moment.
Jim
“””””” Jim Masterson says:
May 9, 2012 at 12:43 pm
>>
George E. Smith says:
May 8, 2012 at 4:41 pm
I wasn’t trying to argue with you George. I think the tidal effect on both sides of an idealized body is the same–if it’s due to a single (idealized) point mass. I also think applying a little limit theory to this problem would demonstrate the mathematics (notice how fast the differences were decreasing in the two examples I presented). But as I said earlier, I don’t have the time at the moment.
Jim “””””
Jim, sorry if my short response may have suggested some criticism of you post. Quite the contrary, and I found your input very helpful. My use of the words “quickie arithmetic” carried no derogatory intent; just that it was a concise input to what the discussion was; pointing out that as Chiefio said, the diurnal tides should be different (and are) because the earth radius is not a negligible fraction of the earth moon distance, particularly in the perigee case. Also if we assume that we have perigee and also a solar or lunar eclipse at the same time (about 7 of those happen each year) then the “maxi tide conditions are even better, and also the orbital inclinations becomes moot.
In any case; accepting that the diurnal tides are different, and favor the case of the moon on the side of the observer who is observing the tide (experimental data), my issue was and is, that because the earth radius IS a negligibly small fraction of the earth sun distance, the new moon versus full moon conditions should result in essentially the same tide, but still with the diurnal tidal difference, that E.M. mentioned. But if one insists that however small the difference between the new moon tides and the full moon tides, actually is, the math should make the SME or EMS tides to be (slightly) greater than the SEM and MES tides, because of the slight remaining non linearity in the idealized geometry situation.
But your analysis shows that the if the observer is on the same side as the moon, the tide is larger than if the moon is on the opposite side from the observer, and with both sun and moon on the observer side, the observer is clearly in daylight; not the darkest of nights.
If I’m not mistaken, the recent maxi all time tide, the fuss was all about was actually a full moon situation, and NOT a new moon situation, thereby providing an existence proof that new moon tides are NOT necessarily the greatest.
So perhaps I didn’t explain it as well as I might have; but clearly, my English language and usage is not on a par with that of Dennis.
But your input is much appreciated Jim.
George
@Dennis Cox:
There are 2 Mr. Smiths in this discussion, so it wasn’t particularly clear which one you were sneering at above. It looks like it was in response to my pointing out the existence of diurnal tides in some places.
As to how it got “injected”, that would due to you:
A simply wrong assertion of fact. Often true, but also sometimes not. It is not an absolute and in fact some places have one tide part of the year and two tides other parts of the year. SAME geography, different tide patterns.
FWIW I don’t care one way or the other about your state of being impressed, or not. It is entirely irrelevant to me. The simple fact is that “reality just is” and there are many places with diurnal tides. You asserted that there was only one case, 2 tides a day. I’m just pointing out that reality is more complex than that.
Since you seem to have confused me with George, I’ll remind you of my experience with tides:
I lived on a 27 foot sail boat in S.F. Bay for a couple of years and owned / sailed it for several more after moving ashore. It was a shallow draft keel (27 inches) and my v-made-good was typically about 3 knots. Less if in a tack. As tides through Raccoon Strait would often exceed that, and I typically had to tack as the wind rarely let me run wing-and-wing downwind straight down the strait, I developed a keen sense of just what the tides were.
Leaving the port at Sausalito at the wrong time and trying to go up current through Raccoon Strait would rapidly put me going backward out the Golden Gate… Though I did spend many a peasant weekend day just tacking back and forth and going nowhere much, but enjoying the play.
OTOH, doing 3 knots in a 3 knot tide going my way I could do pretty well. One of my favorite things to do was plan a circumnavigation of Angel Island. If timed right it could be fun and reasonably fast.
So do please take your sniditude and reserve it for someone who cares. It’s wasted on me.
Then again, if you don’t care to know about what really happens with tides, and that some places only have one cycle per day, that’s fine too. But I’d suggest not trying to run a sailing vessel and stick with motor boats where you can use the engine to save you from the rocks. You will need it.
Oh, and notice that MostlyHarmless has given you another reference, since you didn’t like the wiki, even though it is a rather well written one, as wikis go. And yes, tides ARE complex things. That you seem to reject simple observations of reality is your loss, not mine.
@jim Masterson:
I wasn’t tossing George under a bus. We know each other somewhat. I was (gently I hope) pointing him at some useful reality observations.
There were plenty of times that I could do a Raccoon Strait run on one tide, but not the other. That kind of thing matters when you have 3 knots or less to work with, and it can drop to 1 kt made good with a bit of tacking and / or light winds.
I thought it might be helpful to point that out to George.
@All:
I must be doing something right, I’ve got folks tossing rocks at me from both sides. One for letting George know that his theoretical model didn’t match reality (so siding with Cox) and the other from Cox, for gently letting him know his experience base is narrow and he needs to be aware that reality is more complex than just ‘2 tides a day’ (so siding with George, I guess).
The reality is more ‘not siding with anyone’ and just pointing to bits of reality that matter. But I guess y’all would rather bicker on hypotheticals vs limited experience… so I’ll just bow out now and let you-all go back to flinging stuff at each other…
“”””” E.M.Smith says:
May 9, 2012 at 11:19 pm
@Dennis Cox:
There are 2 Mr. Smiths in this discussion, so it wasn’t particularly clear which one you were sneering at above. It looks like it was in response to my pointing out the existence of diurnal tides in some places. “””””
Well EM, your inputs are always appreciated (anyone else’s too) and you know darn well that I am never looking to round up a posse to (go after) anybody, I always trust you to present your honest views based on your experience. I just never bothered to mention that there were normally the two tidal bulges, more or less opposite each other on earth; I considered that true 8th grade science that need not be even mentioned, so neither wiki nor the other cited “treatise” need be referenced.
But as you point out; and Jim added to; one of those bulges is normally larger than the other; or vierse vicea. Thus ONLY ONE of those two daily tides could be in the maxi tide category; the other is just a wimp, and Jim’s analysis argues the larger one is the tide, being observed by the observer, with the moon over his head, and I don’t disagree with that; hey I grew up with the Pacific ocean on one side of me, and the Tasman sea on the other and less than half a mile apart (at their closest point), so I’ve also seen all kinds of tides. So if the moon up tide is a maxi candidate, and the sun enhancement is also greatest with the sun on the same side as the moon, then in my experience, that is a daytime tide; a new moon tide also, and a maxi candidate if it is also a perigee tide, and a solar eclipse tide.
I’ll leave it to others to decide whether a moon up, new moon (both on same side) maxi tide candidate, is a daytime tide or a night time tide.
As for living on a sailboat in SF Bay, I’ve only once sailed on SF bay, in a 25 footer my boss owned.
Actually for my limited sailing experience, in New Zealand, I’ve actually sailed more on America’s Cup class boats, than any other kind of sail boat, and less so in Solings; always monohull. My most recent sailing was done back in march on a Volvo Ocean racer (70+ footer); well more pedantically it was a Whitbread yacht, and no I wasn’t on it when it placed second in that forerunner of the Volvo Ocean race. I was actually out sailing it while the current flock of Volvo boats, were out doing their in-port Volvo race, the day before they all left Auckland for the Southern Ocean mayhem leg. The boats just arrived in Miami, with American Puma winning the two legs from Auckland, and Itaji, Brazil. I was actually able to get aboard the NZ team boat (Camper), while it was in Auckland, but only at dockside. It placed second last night in Miami, an hour behind Puma, skippered by crack American AC skipper Ken Read.
So I did get to experience some of the local tide conditions in Auckland in March, and in fact Camper, Team NZ used local tidal knowledge to ace everybody else out and run away with the in port Volvo race that day.
But I can’t compete with you living on a 27 footer on SF Bay EM; and I doubt that I’ve had as much fishing time as Dennis.
One should expect an exception to any generalization. There can be an awareness of the daily changes in gravitational force by an observer well away from the sea. From the Australian book Green Mountains, by Bernard O’Reilly, there is an observation by the author, from long experience in timber, that when a tree was felled off the intended line and hung up on other trees, it would frequently fall the rest of the way during the night, at a time that corresponded to high tide at the nearest beach, perhaps a hundred miles away. Whether he was right about a connection, or whether the timing was pure chance, he was certainly aware that there was a daily gravitational variation that might offer an explanation. He made no mention of the daytime high tide; probably only spoke of night time because at night the crash of the tree falling could be heard for miles.