Tuvalu flooding FAIL – no supermoon tide of any significance

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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66 Responses to Tuvalu flooding FAIL – no supermoon tide of any significance

  1. inversesquare says:

    Propaganda at it’s finest:)….

  2. R. Shearer says:

    So long as not too many people run to one side of the island, they should be fine.

  3. Mike Jowsey says:

    “No one was swept away but sea-water flooded the compost pits in which people have been growing their root crops for centuries.”

    So… if they have been growing in these flood-prone pits for centuries, where’s the problem? F’gawds sake, kiwi journos – THINK!

  4. CodeTech says:

    What will it take??? What will it take to convince the unbelievers, the skeptics, the deniers?

    Well, actually, anything. But they’ve got exactly NOTHING.

  5. tango says:

    they don,t tell you that a lot of these islands are sinking naturally

  6. Dennis Cox says:

    How come no one is pointing out that the moon goes through perigee, and gets this close once every orbit?

  7. Smokey says:

    Dennis Cox,

    Someone pointed it out, but I can’t remember where. The difference is that perigee this month coincided with a full moon.

  8. DJ says:

    Funny. No secret gasses involved, no covert emails out of context, just simple physics. Known planet masses, known tidal effects…. very clean mechanics with no obscure feedbacks, and they can’t get it right.

    If the alarmists can’t even get something relatively as simple as some gravitational forces, please, someone, explain to me why the alarmists should be believed when they talk about a complex chaotic system with both positive and negative feedbacks, involving physics AND chemistry??

    ….. Or have we passed the tipping point, and global warming is warping the laws of physics now?

  9. Bennett says:

    “No one was swept away but sea-water flooded the compost pits…”

    I know that in some places an incoming tide can be perilous, but that’s not the rule by any stretch. In researching it a tad, I ran across this story which is really alarming I suppose, but more in an “ashamed to be human” sort of way.

    The fifth picture is amazing!

    Such incompetent photoshopping.

    “It’s a damn wall. Level doesn’t work that way!”

    Be scared not.

  10. Dennis Cox says:

    Yes, But the fact that it’s reflecting more light doesn’t have anything to do with the moon’s gravitational pull on the Earth at perigee. In fact, during a full moon the Earth is between the sun, and the Moon. And the highest tides happen when the moon is at perigee and on the same side of the Earth as the sun. In other words, the highest tides of the year always happen on the darkest nights.

  11. Bennett says:

    @Dennis Yes, But the fact that it’s reflecting more light doesn’t have anything to do with the moon’s gravitational pull on the Earth at perigee.

    Exactly, plus all the rest of what you penned. Full moon, bfd.

  12. DaveG says:

    Yesterday I/my super catastrophe model made the easiest prediction in the world, Now do I get some of that global warming grant money?

    DaveG says:
    May 5, 2012 at 6:21 pm

    As I breathlessly write this Tuvalu and surrounding Atoll isles only have only 6 hrs left before the evil super moon destroys all in it’s deadly gravity grip. I won’t sleep tonight worrying about the Tuvaluanees. Where will they store the $billions in global warming guilt money from the western taxpayers with the Banks and island banksters underwater!
    / Sarc off
    Seriously tomorrow will dawn the ocean will be the same depth as yesterday and the sun will shine as usual on the doom, gloom and the users on Tuvalu and the egg on their face warmers!

  13. Ian Cooper says:

    Mike Jowsey,

    if our Kiwi journos, or any others for that matter, stopped to think about it they’d realize that there was nothing sensational in it so they would have to go and invent something else to sell their fish’n’chip wrappers with!

    The worst part about it is, no matter what we do or say here there will always be a big group of extremely gullible people who also won’t take the time to think about it or ask the right questions. That is human nature and that is what we are dealing with. Going by the hits on this site those people are more and more in the minority. If only we could convince the politicians that it is the case!

    Cheers

    Coops

  14. G. Karst says:

    Bennett says:
    May 6, 2012 at 8:34 pm

    Exactly, plus all the rest of what you penned. Full moon, bfd.

    It is no bfd for tides, but if you live in the country, away from city lights, the last few nights have been spectacularly bright. Eerie if one has never experienced it. GK

  15. I have to say that since I’ve moved to the Southern Hemisphere (and I love it here) that the local media is particularly prone to Greenish Warmism. When the rest of the world has watched Carbon Trading fail miserably, the Labor Gov in Australia is just about to implement a carbon tax.
    I hate to say it but I think we’re a bit behind the times down here!

  16. toyotawhizguy says:

    The good news for Tuvalu and other low elevation islands is that by analyzing the two-way transit time of pulsed laser beams aimed at retroreflectors placed on the surface of the moon by NASA, astronomers have determined that the moon is steadily receding from the earth by about 4 centimeters per year. Although the effect on the tides is miniscule in our lifetimes, the effect is cumulative.
    The bad news is that it will take over 20,000 years from the present day until the moon has receded sufficiently to lower the tides by an amount sufficient to have an impact on inhabited low elevation islands.
    A good analogy to the steady increase in the moon’s average orbital radius would be a clock that gains 3 milliseconds per year. After 20,000 years, without any adjustments, the clock will have gained 60 seconds.

    The big question is who or what will be around 20,000 years in the future to benefit from this?

  17. joe says:

    Hopefully it doesn’t tip over. Do we have an army base there? :/

  18. Len says:

    DJ says:
    May 6, 2012 at 8:15 pm
    “Funny. No secret gasses involved, no covert emails out of context, just simple physics. Known planet masses, known tidal effects…. very clean mechanics with no obscure feedbacks, and they can’t get it right.”

    DJ:
    I don’t know if they have any physists or other hard science types left in the NZ govt research organizations. The rush has been to “community based”, social science, environmental science and other such leftists posing as real scientists. They are mostly activists and hard core leftists just as are they in the UK Met, USA NASA, NOAA, USGS, Etc. San.

  19. Neil Jones says:

    Today I’m feeling like a bear of very little brain…but doesn’t the moon hit perigee at some point of every month? Surely the only thing this time was that it almost coincided with Full-moon giving us a spectacular show.

  20. Nigel S says:

    ‘king tides will get you every time.

  21. George E. Smith says:

    Talk about stuff and nonsense. All the Bay area radio and TV “news” stories said the moon would be 15% bigger and 30% brighter.
    I don’t know about you, but when someone tells me that it means “than last night” or “than tomorrow night.

    Even the Volvo ocean Race boats now zipping through the Bahamas on their way to Miami, got into the mega hype, saying that the moon was so bright that they didn’t need the strobe lights to illuminate the sails (so they can trim them for optimum performance). Like they didn’t notice the damn moon was just as bright the night before, and will be just as bright tonight; just not quite round.

    These idiots don’t seem to know anything about orbital mechanics, and just how very slightly elliptical, the moon and earth orbits actually are.

  22. Richard111 says:

    2.9 metres! HAH! High tide today at 06:40 gmt was 7.4 metres.

  23. Marian says:

    “inversesquare says:
    May 6, 2012 at 7:12 pm

    Propaganda at it’s finest:)….”

    Yeah. That pretty much sums it up.

    The NZ Herald has lost the plot when it comes to the amount of utter drivel it passes off as Climate Change stories. You’d think the MSM would give it up re Tuvalu and sea levels rises because its NOT a major real issue only in AGW/CC Fantasyland!

    Having said that. I suppose you can’t expect anything better from the NZ Herald. Since its part of the Fairfax Media which have investments in Earth Hour organisation!

  24. George E. Smith says:

    “”””” nnis Cox says:

    May 6, 2012 at 8:20 pm

    Yes, But the fact that it’s reflecting more light doesn’t have anything to do with the moon’s gravitational pull on the Earth at perigee. In fact, during a full moon the Earth is between the sun, and the Moon. And the highest tides happen when the moon is at perigee and on the same side of the Earth as the sun. In other words, the highest tides of the year always happen on the darkest nights. “””””

    No way Jose, the new moon and full moon tides are the same on average. There are two tidaal bulges; one on each side of the earth, and it diesn’t matter which side the sun and moon are on, given that you have a certain sun distance and a certain moon distance for the two cases of full moon and new moon.

    Time to re-examine why there are tides at all Dennis.

  25. George E. Smith says:
    May 6, 2012 at 10:48 pm

    “No way Jose, the new moon and full moon tides are the same on average. There are two tidaal bulges; one on each side of the earth, and it diesn’t matter which side the sun and moon are on, given that you have a certain sun distance and a certain moon distance for the two cases of full moon and new moon.”

    Not well thought out, neither was Dennis’ comment. The Earth has a natural oceanic bulge centred on the equator, The Moon and Sun tidal bulges are superimposed on this, but at different angles to the plane of the equator. The two tidal bulges aren’t exactly symmetrical, they’re highest in the direction of the Moon & Sun, most pronounced for the much larger Moon bulge. This is because the Moon doesn’t rotate around the centre of the Earth, both rotate around their common centre of gravity, which is some distance away from Earth’s centre, and the mass of water offsets the monthly wobble the Earth experiences. When the Moon is closer, its bulge is higher, and at full Moon it’s aligned with the Sun’s tidal bulge. This is the time of spring tides, and the Moon’s perigee magnifies the effect when it coincides with a spring tide, the “Supermoon”.

  26. Disko Troop says:

    Surely the term should be “gravitational squeeze” of the moon as the high tide on the far side of the Earth would be a “push” as opposed to the “pull” on the side nearest to the moon.

  27. I intended to add that tide predictions are based on tidal mechanics. The final outcome depends on other factors also; the biggest effect is atmospheric pressure. A 1 millibar change results in approximately 1 cm change in sea level; lower pressure, higher sea level. Wind also has an effect, so a deep depression with winds in an unfavourable direction could have resulted in a tide which exceeded the prediction by at as much as 10-20 cm, possibly even more if a strong cyclone was passing. Add in surface temperature which can expand or contract the surface layer to further complicate matters, and wipe the smug grin off some faces.

  28. Mike Busby says:

    No need for waders to check my letterbox today for 2 reasons. No abnormally high tide and it was a public holiday so no mail delieveries.

  29. Jimbo says:

    Just how many failures do we have to endure before they finally own up and tell us they were simply trying to pull the wool over our eyes? Fail, fail and fail again.

  30. Rick Bradford says:

    People only remember the initial hype: (“Jones found with underage girls”) and never the retraction (“Sorry, Jones not found with underage girls”) and as the media is overwhelmingly Left/Green oriented, you rarely see any sort of retraction at all.

    The hype, or lie, whatever you want to call it, has done its work. Ask Alinsky.

  31. Curiousgeorge says:

    It wasn’t too long ago that Oracles who were wrong suffered severe consequences. Especially if their predictions cost the King some embarrassment or treasure. Perhaps that risk should be re-instituted.

  32. David says:

    Yet STILL the BBC’s Richard Black is reporting on an upcoming climate conference which of course will discuss, amongst all the other scare stories, RISING SEA LEVELS….

  33. SPreserv says:

    Someone has to remove the moon alltogeteher to save us all from future peril scenarios.
    It will also stop the earth from wobbling and werewolves and …
    /also sarc

  34. Peter Crawford says:

    @ Dennis Cox and @Neil Jones – As I pointed out on the original thread. The Moon is at perigee once every 27.5 days and a full moon perigee occurs every 411 days. The effect these common, well known events have on tides on Earth is trivial.

    Furthermore, it follows that several other of the 13 0r 14 full moons occurring during that 411 day period will be at a time when the moon is very close to perigee. Usually about 3 or 4 of them. So this “14% bigger than any other this year” is arrant nonsense. BTW the accepted difference in apparent size between the full moon at perigee and the full moon at apogee is 11.5%.
    I can guess how they concocted the 14% figure but can’t figure out WHY.

  35. Ulrich Elkmann says:

    “Total predictive failure”.
    Could be the motto of the whole eco/green/save-the-XXXes movement(s). Starting with Rachel Carson (if not Parson Malthus). Nothing but doom ‘n’ gloom forecasts, unrelentingly.
    And not a SINGLE hit in their favor.
    (At least by now we don’t have to wait x decades to that to become obvious. Just 2 days.)

  36. alan says:

    Like children telling tall tales about monsters under the bed to get attention! It’s a shame that big media organizations encourage this kind of childish scaremongering. There seem to be few adults in their audiences.

  37. Person of Choler says:

    You don’t have to travel to balmy Polynesia to find sea level alarmists. The Washington State Department of Ecology solicits from the public photographs of water levels at the highest tides to be used, they say, in preparation for the impacts of climate change:
    http://www.ecy.wa.gov/climatechange/ipa_hightide_map.htm
    The department certainly has all the data to necessary to support the analysis they think they need to do, but such an exercise is a good excuse for greenie beach excursions and it yields images useful in warmist propaganda. Doubtless, flocks of high school students herded by concerned educators descend on the beaches on the appropriate dates.

  38. Ed Mertin says:

    I do not see anything wrong with what Dennis Cox had to say, looking at this…

    http://www.onr.navy.mil/focus/ocean/motion/tides1.htm

  39. Dennis Cox says:

    Thanks Ed Mertin,

    I should part out that I didn’t make that statement about the highest tides of the year being on the darkest nights based on reading any specific blog, or paper. But simply from the personal perspective of one who lived with the tides for years in a little fishing town on the Willapa Bay in southwestern Washington.

    A common local saying there is “When the tide goes out, the table’s set.” The Willapa Bay is Large, and shallow. And those who want to dig for clams, or work their Oyster beds, who don’t pay attention to the tides can run aground, and get stranded for long hours at a time. And since the weather can quickly turn choppy and dangerous while you are stuck on a sand bar out in the middle of the bay, tidal mistakes can get you killed.

  40. woodNfish says:

    I find it telling that none of the media reports included the fact that the perigree moon has occured at least once a year, every year. No, they wanted to pump this up as something unique and potentially disastrous to sow fear and try and link any disasters with AGW. This was never anything more than fear-mongering and propaganda.

  41. George E. Smith says:

    “””””
    me to re-examine why there are tides at all Dennis.

    MostlyHarmless says:

    May 7, 2012 at 12:51 am

    George E. Smith says:
    May 6, 2012 at 10:48 pm

    “No way Jose, the new moon and full moon tides are the same on average. There are two tidaal bulges; one on each side of the earth, and it diesn’t matter which side the sun and moon are on, given that you have a certain sun distance and a certain moon distance for the two cases of full moon and new moon.”

    Not well thought out, neither was Dennis’ comment. The Earth has a natural oceanic bulge centred on the equator, The Moon and Sun tidal bulges are superimposed on this, but at different angles to the plane of the equator. “””””

    Actually quite thoroughly thought out; but reduced to a simple geometry problem of a symmetrical earth, to simply adress the issue of whether the side the moon is on matters. (it doesn’t) Your more elaborate real earth case seems to have forgotten that the earth is not even symmetrical in shape, so the reality is even more complicated than you suggest; not to mention that the non uniform arrangement of the land masses messes it up even more.

    Reduce it to the simplest geometrical symmetry, and then explain why it matters which side the moon is on, when aligned.

  42. Dennis Cox says:

    George E. Smith says:

    “Reduce it to the simplest geometrical symmetry, and then explain why it matters which side the moon is on, when aligned.”

    It matters because when the moon is at perigee and at the same time is aligned between the sun, and the Earth, the gravitational pull that creates the tides is maximized. You can get all anal about demanding a better, more scientific explanation than that if you like. It’s not clear what your definition of "well thought out" is. But when you’ve lived a fisherman’s lifestyle that’s been intimately connected with the rising and falling of the tides for a few years, (and a couple of thousand tides) the simple subjective observation that the highest tides happen on the darkest nights becomes an observation based on years of direct experience.

  43. Tom_R says:

    Peter Crawford says:
    May 7, 2012 at 7:01 am
    @ Dennis Cox and @Neil Jones – As I pointed out on the original thread. The Moon is at perigee once every 27.5 days and a full moon perigee occurs every 411 days. The effect these common, well known events have on tides on Earth is trivial.

    This ‘super moon’ aligns very close to the ecliptic; there’s an annular solar eclipse at the next new moon. That has to add a little to the tide height compared to the typical full moon perigee.

    Also, due to the rotation of the Earth the tidal bulge is east of the point where the moon is directly overhead. To the observer the bulge occurs after the moon has crossed the meridian.

  44. Gunga Din says:

    Tuvalu is still there.
    In looking into tides I came across abit of info that I once knew but had forgotten. Just as there are tidesw in the ocean, there are tides in the atmosphere. As the air is pulled toward the Moon (or the Sun) they can actually cause a “breeze” of about 0.05 mph. So, I think all these stories about the “Super Moon” submerging Tulavu were caused by the “Super Moon” itself. It must have pulled the oxygen out of all those newsrooms.

  45. Pamela Gray says:

    I’m Irish, born in July under the moon, and DEFINITELY got swept away Saturday night. What a fun event!

  46. When the sun and moon are directly across the earth from each other to make the king tides in the ocean they also combine the tidal effects in the atmosphere, as the declinational angle at culmination shifts through the 18.6 year Mn cycle, there results in a gradual shift in the time of year that the moon and sun are both closest to the ecliptic plane at the same time. The atmospheric tidal effect of this both on the ecliptic plane produces the blocking highs that drift through the seasons due to the progression of declinational angle extent and the procession of the lunar nodes on a ~9 year pattern. If you look at the past occurrence of these patterns and use them as an analog for forecasting the pattern of blocking highs, past and present you will find the Russian heat waves and the Pakistani floods are predictable to with in a couple days.
    From looking at the entire pattern you could forecast the occurrence of almost all blocking highs (which the standard numerical models cannot do yet, as the info is not included in the model, WUWT?

  47. George E. Smith says:

    “”””” Dennis Cox says:

    May 7, 2012 at 1:32 pm

    George E. Smith says:

    “Reduce it to the simplest geometrical symmetry, and then explain why it matters which side the moon is on, when aligned.”

    It matters because when the moon is at perigee and at the same time is aligned between the sun, and the Earth, the gravitational pull that creates the tides is maximized. You can get all anal about demanding a better, more scientific explanation than that if you like. It’s not clear what your definition of “well thought out” is. But when you’ve lived a fisherman’s lifestyle that’s been intimately connected with the rising and falling of the tides for a few years, (and a couple of thousand tides) the simple subjective observation that the highest tides happen on the darkest nights becomes an observation based on years of direct experience. “””””

    Well Dennis, being as you are an experienced fisherman; I’m going to bow to your assertion that the gravitational pull of the moon and the sun is maximised when the sun and the moon are on the same side of the earth, and since the moon is closer to the earth than the sun is, that would put the moon between the earth and the sun, so they are both pulling on the oceans in concert.

    For most locations on planet earth, that would also make it daylight rather than the darkest of nights.

    So if your fishing lifestyle observations are correct, that would imply that on the darkest of nights, with the sun and the moon both being on the opposite side of the earth, then they both must be PUSHING the oceean away under your boat rather than PULLING on the ocean.

    Sorry Dennis, you can’t have both the sun and the moon pulling in concert on the ocean closest to them, and have it be the darkest of nights; it has to be daylight; maybe its the brightest of days, with both the sun and the moon illuminating the earth over that maxi tide.

  48. Ed Mertin says:

    George, please click onto the link that I provided.

    The key to tides is the varying strength of the Moon’s gravitational pull on different parts of the globe. The Moon pulls most on the water nearest to it,creating a high tide bulge of water. On the opposite side of the planet,about 7,926 miles (1,2760 km) away,the Moon’s pull is much weaker and the water is left to form another high tide bulge. Low tides are found halfway between the highs. The rotating Earth carries us through these regions of high and low water.

    When the Moon,Earth,and Sun fall in a straight line, which we call syzygy (siz-eh-gee),we notice the greatest difference between high and low tide water levels. These spring tides occur twice each month,during the full and new Moon. If the Moon is at perigee,the closest it approaches Earth in its orbit, the tides are especially high and low.

  49. Dennis Cox says:

    Mr Smith there are two high tides, and two low tides every day.

  50. George E. Smith says:

    “””””
    Ed Mertin says:

    May 7, 2012 at 11:08 pm

    George, please click onto the link that I provided.

    The key to tides is the varying strength of the Moon’s gravitational pull on different parts of the globe. The Moon pulls most on the water nearest to it,creating a high tide bulge of water. On the opposite side of the planet,about 7,926 miles (1,2760 km) away,the Moon’s pull is much weaker and the water is left to form another high tide bulge. Low tides are found halfway between the highs. The rotating Earth carries us through these regions of high and low water.

    When the Moon,Earth,and Sun fall in a straight line, which we call syzygy (siz-eh-gee),we notice the greatest difference between high and low tide water levels. These spring tides occur twice each month,during the full and new Moon. If the Moon is at perigee,the closest it approaches Earth in its orbit, the tides are especially high and low.

    Dennis Cox says:

    May 8, 2012 at 5:58 am

    Mr Smith there are two high tides, and two low tides every day. “””””

    To Ed and Dennis,

    If you have been working and earning a living for more than 52 continuous years as a working Physicist; then you probably know much more about Physics, and the Physics of Orbital Mechanics, and of Tides, than I do.

    If you look back over this thread, you will see that it was Dennis who said that the sun and the moon have to be ON THE SAME SIDE OF THE EARTH for the highest tides; thereby indicating that the tidal bulge on THE OPPOSITE SIDE of the earth, which is in the DARKEST NIGHT condition is somehow a bigger bulge, than the one on THE SAME SIDE of the earth as the sun and moon, which is in the BRIGHTEST DAYLIGHT condition.

    So he’s the one claiming from his fishing experience that the two tidal bulges are different heights, and the one on the dark side is somehow the highest.

    I SIMPLIFIED the problem to a clean symmetrical geometry of a uniform oblate spheroidal earth, and eliminated the complexities of the continental locations and all the other factors that do in fact make th complete tidal picture more complex, so that it was a simple (idealized) three body orbital mechanics problem , and I don’t know how many times I actually did the math for students that shows that first order, the two bulges are the same on both sides of the earth, and it is irrelevent which side the sun or the moon is on, they each (alone) would produce two equal tidal bulges on opposite sides of the earth, so it only matters that sun earth and moon be colinear to get the highest tide (ON BOTH SIDES OF THE EARTH SIMULTANEOUSLY).

    So SEM works equally as well as SME, or EMS, or MES to produce the highest tides.

    Two of those cases are daylight tides, and two are nightime tides, and daytime is not the darkest night. I suppose a total eclipse of the sun, would produce the darkest night on the opposite side, depending on planetary and stellar configurations; perhaps seen in North Korea.

    But as I said; maybe you chaps have been at it longer than I.

  51. Dennis Cox says:

    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.

  52. E.M.Smith says:

    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

    Tides are most commonly semi-diurnal (two high waters and two low waters each day), or diurnal (one tidal cycle per day). The two high waters on a given day are typically not the same height (the daily inequality); these are the higher high water and the lower high water in tide tables. Similarly, the two low waters each day are the higher low water and the lower low water. The daily inequality is not consistent and is generally small when the Moon is over the equator.[6]

    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)

    Because the gravitational field created by the Moon weakens with distance from the Moon, it exerts a slightly stronger force on the side of the Earth facing the Moon than average, and a slightly weaker force on the opposite side. The Moon thus tends to “stretch” the Earth slightly along the line connecting the two bodies. The solid Earth deforms a bit, but ocean water, being fluid, is free to move much more in response to the tidal force, particularly horizontally. As the Earth rotates, the magnitude and direction of the tidal force at any particular point on the Earth’s surface change constantly; although the ocean never reaches equilibrium—there is never time for the fluid to “catch up” to the state it would eventually reach if the tidal force were constant—the changing tidal force nonetheless causes rhythmic changes in sea surface height.

    Semi-diurnal range differences

    When there are two high tides each day with different heights (and two low tides also of different heights), the pattern is called a mixed semi-diurnal tide.

    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??”

  53. E.M.Smith says:

    @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:

    Careful Fourier data analysis over a nineteen-year period (the National Tidal Datum Epoch in the U.S.) uses frequencies called the tidal harmonic constituents. Nineteen years is preferred because the Earth, moon and sun’s relative positions repeat almost exactly in the Metonic cycle of 19 years, which is long enough to include the 18.613 year lunar nodal tidal constituent. This analysis can be done using only the knowledge of the forcing period, but without detailed understanding of the mathematical derivation, which means that useful tidal tables have been constructed for centuries. The resulting amplitudes and phases can then be used to predict the expected tides. These are usually dominated by the constituents near 12 hours (the semi-diurnal constituents), but there are major constituents near 24 hours (diurnal) as well. Longer term constituents are 14 day or fortnightly, monthly, and semiannual. Semi-diurnal tides dominated coastline, but some areas such as the South China Sea and the Gulf of Mexico are primarily diurnal. In the semi-diurnal areas, the primary constituents M2 (lunar) and S2 (solar) periods differ slightly, so that the relative phases, and thus the amplitude of the combined tide, change fortnightly (14 day period).

    Tides are very complex beasts and the description of the calculation in the wiki is, er, not simple.

  54. Jim Masterson says:

    >>
    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

  55. Dennis Cox says:

    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.

  56. 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.

  57. Dennis Cox says:

    MostlyHarmless Said:

    "highest perigee spring tides occur for a combination of perigee and NEW moon, not full moon as has just occurred."

    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.

  58. Diurnal tide predictions at Fremantle & Hillarys, WA here:

    http://www.bom.gov.au/oceanography/tides/MAPS/wa.shtml

  59. George E. Smith says:

    “””””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.

  60. George E. Smith says:

    “”””” 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.

  61. Dennis Cox says:

    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:

    “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.”

    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.

  62. Jim Masterson says:

    >>
    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

  63. George E. Smith says:

    “””””” 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

  64. E.M.Smith says:

    @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:

    Dennis Cox says:
    May 8, 2012 at 5:58 am

    Mr Smith there are two high tides, and two low tides every day.

    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…

  65. George E. Smith says:

    “”””” 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.

  66. cadet31 says:

    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.

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