Jonathan White holding a surf board.

Jonathan White has been thinking about the tide, and the mysterious process behind it, for most of his life. As a young surfer in Southern California, White found the tide often dictated the quality of the surf. In Alaska, White almost lost a boat when it ran aground in a spring tide, and in the Puget Sound, White spent several years hosting “floating seminars” from a 65-foot schooner. In his new book, “Tides: The Science and Spirit of the Ocean,” White travels across the Arctic, China, Europe, Latin America and Mavericks, the famed big-wave surf spot, to meet the people whose cultures are impacted by tides and sea level rise. White joins us to discuss the complexity of tides, including why great thinkers like Plato and Descartes were confounded by them.

Jonathan White’s ‘Tides’ Explores ‘The Science and Spirit of the Ocean’ 14 March,2017Michael Krasny

Jonathan White, author, "Tides: The Science and Spirit of the Ocean"

  • Ben Rawner

    I recently read a great children’s book called “Fog is the Breath of the Ocean” that spotlights how all of the ocean is connected. What are some other ways we can teach the future generations about how important our ocean knowledge is?

  • Chuck

    What research or development of tide and wave energy is being conducted in the bay area or the US? Where and by whom is such energy being produced at this time or on the verge of production?

  • Chris Plakos

    Jonathan, does your book explore anything about the tides of the atmosphere? Can you speak to any atmospheric tide phenomena?

  • Fay Nissenbaum

    Please explain about the tides of our own Ocean Beach, San Francisco. Its rough tides have fooled and injured experienced surfers. Also, the mouth of the Golden Gate is fraught with skipper-challenging tide complications. Thanks for an interesting discussion!

    • jurgispilis

      The tides at Ocean Beach are hugely effect by the Golden Gate. At flood tide all this ocean water is pouring into the bay, up along the coast from the south, and down the coast from the north. At ebb tide, all this water is flowing pout of the bay, and down the coast to the south, and up the coast to north. San Francisco Bay makes the Ocean beach tides so rough.

  • Ehkzu

    Some of the richest, most diverse habitats on Earth are caused by tidal currents: they are the coral reef habitats found in the channels between tropical islands. Soft corals inflate when the tide is running; crinoids crawl out onto sea fans to harvest plankton, along with other plankton feeders like sea apples, and whale sharks may visit. Scuba divers enjoy all this of course, though we’re also endangered by the tides. Once I was blown off a reer near New Guinea and wound up by myself, being driven out to sea, with no boat in sight. It wasn’t too long before they found me…but it felt a lot longer.

  • Kevin Skipper

    I like that story about the sandpipers. Never know that their weight was comparable to a pinp-pong ball.

    What about the Pacific Golden Plovers that fly non-stop from California’s coast to Hawaii. During their stay in the islands, they are called ‘Kolea.’ Seems that these beauties are also quite perfidious. Some accounts credit the birds for helping lead Captain James Cook to ‘discover ‘ the chain, it’s people and the natural paradise in which they lived.

    • William – SF

      You can see them at Ocean Beach -winter — dog on leach only, please. While visiting the outer Sunset grab a cortado at Andytown on Lawton at 43rd, or Trouble (to me they’re Troubled) on Juda. Andytown has a Snowy Plover coffee drink for the full circle experience.

      • Kevin Skipper

        So you’re that saying outside Hawaii, the venerated Kolea is whitewashed into the Snowy Plover? Disgraceful.
        I remember now, their colors change during their migration.

        • William – SF

          Half cup of cold bubble water, shot of espresso, covered with half-cup of cream. Wholly whitewashed and thoroughly disgraced! (Sells like mad, too.)

  • De Blo

    Great to hear the guest reference Mont Saint Michel. I visited there and absolutely had the experience of seeing the tide rush in and absolutely did feel closer to God. The ocean in general is a spot where one can really feel God’s presence in a concrete and transcendent way.

    • jurgispilis

      There was a great 1990 movie “MindWalk” with Liv Ulman, Richard Dreyfus, and Sam Wasserman. A pysicist, a Senator, and a poet. All filmed at Mt. St. Michelle. There was a scene in the torture chamber. When I visited that island, i looked for the torture chamber. There is no torture chamber at MSM!

  • William – SF

    Centrifugal force – an apparent force that acts outward on a body moving around a center, arising from the body’s inertia
    Centripetal force – moving or tending to move toward a center

  • Annie Lopez

    What does the tie and a moon have to do with regulating the woman’s menstrual cycle if any?

  • Robert Thomas

    “… [B]ecause of centrifugal force …”


    The presence of both the sun and the moon is responsible for both daily tides, the high tide on the side of the Earth closest to the Moon AND for the high tide on the side of the Earth farthest from the moon. When the Sun and Moon are in either the same direction away from the Earth or when they are in antipodal directions from the Earth, the tides are highest on both sides of the Earth at the same time. When the Moon and the Sun are 90° from one another (“neap” tide), the forces these two bodies have on the oceans partly cancel. See this graphic:

    The oceans of the Earth amount to a thin-sheet spheroid that is made “prolate” (football shaped) primarily by the sum of the gravitational forces of the Sun and Moon, by the rotation of the Earth on its axis and by the coriolis force.

    The reason that the oceans also bulge on the side of the Earth farthest from the Sun and Moon is because every bit of matter is attracted to every other bit of matter in proportion to the product of the masses of each of the two bits and in inverse proportion to the square of the distance between them. Mathematics that assumes this simple relation predicts that both “bulges” exist simultaneously.

  • Robert Thomas

    It would have been good to note that the rocky crust of the Earth and the deeper mantle of the Earth are also affected by the gravitational forces that also result in the oceans’ tides. Parts of the land (and seafloor) surface of the Earth change their distance from the Earth’s center by as much as two feet, twice a day.

    Through the action of the tidal gravitational forces of the Moon and the Sun, the rotational kinetic energy stored in the Earth (currently 2.138×10^29 Joules) is very slowly turned into heat.

  • Matt M.

    The Great Lakes are non-tidal bodies of water. They do not experience true tides, but rather atmospheric phenomenon from meteorological effects…

    • Robert Thomas

      These lakes experience tides. Their magnitude is negligible, compared to the effects of weather.

      • Matt M.

        The tides experienced by the Great Lakes, and by extension, all lakes and closed bodies of water, cannot experience true tides. They experience seiches, but not true tides…

        From NOAA:
        True tides—changes in water level caused by the gravitational forces of the sun and moon—do occur in a semi-diurnal (twice daily) pattern on the Great Lakes. Studies indicate that the Great Lakes spring tide, the largest tides caused by the combined forces of the sun and moon, is less than five centimeters in height. These minor variations are masked by the greater fluctuations in lake levels produced by wind and barometric pressure changes.

        Consequently, the Great Lakes are considered to be non-tidal…

        Wind and weather conditions on the Great Lakes may create a seiche, an oscillating wave which can be several feet high. In many of the Great Lakes, the time period between the “high” and “low” of a seiche may be between four and seven hours. As this is very similar to the six-hour time period of the tides on the ocean, it is frequently mistaken for a tide.

        • Robert Thomas

          I think that’s what I wrote…

          “True tides—changes in water level caused by the gravitational forces of the sun and moon—do occur in a semi-diurnal (twice daily) pattern on the Great Lakes.” [emphasis added]

          They are negligible in amplitude, compared to the effects of other mechanisms.

          There is no way that a body of water on the Earth can escape the gravitational force of the Sun and Moon.

          • Matt M.

            Fair point…

            But the gravitational, tidal force from the Moon that “squeezes” or, in reality, pushes (not pulls) water towards the Moon affects all bodies of water by that same logic. Because closed bodies of water, including swimming pools, cups of water, and us (humans, which are basically sacks made up of 70% water) are all essentially “squeezed” a tiny bit by the moon’s gravitational pull, all of those things experience the same microscopic tides that you would see in the Great Lakes. Granted, the Great Lakes being as massive as they are allows for a slightly larger increase/decrease in tidal height (namely, a few centimeters, versus the micrometers or less in differential height for very small bodies of water), but everything experiences those same microscopic changes in tidal height, including parts of the Earth’s crust housing the bodies of water. Therefore, in general, closed bodies of water, including lakes, are considered non-tidal bodies of water…

            PBS Spacetime does a fantastic job of explaining the gravitational phenomenon that results in tidal forces pushing water towards the Earth-Moon Line:

          • Matt M.

            After reading through your comment, I think we’re in agreement and saying the same exact thing… Sorry, don’t mean to argue for the sake of arguing, just thought the listeners should be fully aware that tidal forces are not a pulling of water in the direction of the Moon, but rather a radial gravitational attraction towards the Moon… and it’s applicable to everything on Earth, very much in agreement with your other comment on the rocky crust and mantle of the Earth that is also affected by the tidal force of the Moon…

          • Robert Thomas

            I ought to have made my assertion slightly differently. I should have written something like, “These smaller bodies of water react in the same manner as the oceans to the gravitational force that causes tides but proportionately less so; however, if saying that a large lake (or small sea) experiences tides means that it experiences such changes that humans can usefully mark due to this force, then we should say they are not tidal.” Or something like that.

            But many misunderstandings accrete when we demand that scientific language respect the requirement that phenomena closely relate to physical behavior at human scale (inches; meters; fathoms). The sticky part comes when we note that scientists routinely apply “tide” and “tidal force” to describe the phenomena not only of the Earth’s oceans but of others much divorced from our human scale. For example, the perturbation of a comet’s shape in the vicinity of a gas giant planet; the creation and maintenance of a gas giant’s rings; The deformations of colliding galaxies; the smashing of a companion star in the vicinity of a black hole; vulcanism on Jupiter’s moon Io – are all said to be due to tidal force.

            What really irks me is that a guy who’s written what I’m sure may be a worthwhile and even poetic book all about tides has chosen to insert the word “science” into the title of his book while clearly not understanding at all what causes them and who was utterly unable to correctly answer the very fair question how it is that there are simultaneous equipotential antipodal tidal bulges of its thin water sheet. The invocation of “centrifugal force” was just spurious and was misleading, for all listeners. He doesn’t understand the mechanics that explains this riddle, which was solved by eighteenth century theorists and which many of us learned in eleventh grade physics. Rather than just saying, “It’s Newtonian physics” or “That’s how gravitation works” or even just “I don’t know” – all of which would have been fine – he tossed out a brain flatus.

          • Matt M.

            Completely and wholeheartedly agree… The mentioning of centrifugal force is extremely misleading, an extremely egregious misstep that propagates many misconceptions of classical mechanics, especially of how rotational motion actually works…

            Tidal forces are a complicated topic, that, as the video in link that I attached to my previous post says, even veteran physicists may explain incorrectly. Most people don’t understand antipodal tidal points, let alone explain them in a way that is easily understandable… Despite this, I don’t know that I can be as forgiving: in my personal opinion, it’s incredibly irresponsible to tout the physics of tides using incorrect science and misinformation. One must be very careful and cautious on how the science is explained… Otherwise, it can be misleading to the readers who take the incorrect information forward…

            For anyone who is interested in the more detailed explanation, the NOAA has a good, albeit a bit dense, explanation of the science behind tides:

            Additionally, for those of who think that “centrifugal force” is a real thing, remember that Newton’s First Law of Motion is the Law of Inertia: it states that an object in motion will stay in motion until acted upon by an unbalanced force. If you are in a car going around a bend such as on an exit off-ramp, you (as in your person) will continue to move in a linear trajectory that is tangential to the curvature of the car moving around the bend… it isn’t until the car seat or car door “pushes” you in the direction of the car that your trajectory is changed… a “centrifugal force” acting upon you to correct your line of motion to align with that of the car, which is not a force, but something that arises due to inertial motion. Because velocity is a measure of not only your speed but your direction as well, you and your car moving in a circular path are accelerating, since the direction of the motion is changing as you move around the circle, even if the speed (the magnitude of your velocity) is constant, i.e. even if you are not speeding up or down the car. The rotational acceleration is what provides objects moving in circular paths a centripetal force (i.e. a “center-seeking” force). Ever ask why a dryer rotates a drum instead of just heating the clothes without any motion or why a washer spins the clothes to dry the clothes a little bit before placing the clothes in the dryer? The rotational motion of the dryer’s (or washer’s) drum forces water droplets to move off the clothes into the drum, since the water droplets move tangentially to the clothes as they rotate with the drum. The water will only stop moving in a line towards to the drum of the dryer once it hits the drum’s wall… It’s only then that the water will move with the drum, in the circular path in which the drum wall is moving…

            Anyways, I’d advocate for anyone who is interested in the science to do some research before believing any single source of information (including myself)…

          • Robert Thomas


            I think that the NOAA article represents that the tide bulge on the side of the Earth pointing in the direction opposite the combined vector force of the gravitational field of the Sun and Moon is produced by centrifugal effect of the Earth and Moon as they rotate (every 28 days) around the barycenter of their masses. I think that this is completely wrong.

            I was taught that no rotational motion at all is required to maintain BOTH tidal bulges, even if the Earth and Moon were in free fall. A short Google search to refresh my memory resulted in

            Mathematical treatment
            “Tidal acceleration does not require rotation or orbiting bodies; for example, the body may be freefalling in a straight line under the influence of a gravitational field while still being influenced by (changing) tidal acceleration.”

            “Tidal force”

            In other words, the resulting force along the axis of the Moon and the Earth (setting aside the Sun’s effect, without loss of generality) – even if the system is in free fall and with no angular momentum – results in the axial acceleration a of the thin water sheet given (using a Taylor series expansion and subtracting the Force of the Earth’s own gravity, assumed to be spherical) by

            a ≅ ± r(hat)•2∆rG•M/R^3

            a is the acceleration felt by particles in the Earth’s thin water sheet along the system axis;
            r(hat) is the unit vector pointing from the Moon to the Earth;
            r is the Earth’s radius;
            M is the mass of the Moon;
            R is the distance between the centers of Earth and Moon]

            which is toward the moon on the side of the Earth closest to the moon and away from the moon on the side of the Earth farthest from the Moon. This WP article comports with my understanding and recollection better than the NOAA article.

            The NOAA article seems to require that the antipodal water particles bulge away from the barycenter of the Earth/Moon system even though the Earth is turning 28 times faster than the system is rotating – I may be missing something but if angular momentum were the reason for the antipodal bulge it would require it to act in some weird epicycloid motion – unless the oceans were still with respect to the moon and the Earth turned under them every day.


Michael Krasny

Michael Krasny, PhD, has been in broadcast journalism since 1983. He was with ABC in both radio and television and migrated to public broadcasting in 1993. He has been Professor of English at San Francisco State University and also taught at Stanford, the University of San Francisco and the University of California, as well as in the Fulbright International Institutes. A veteran interviewer for the nationally broadcast City Arts and Lectures, he is the author of a number of books, including “Off Mike: A Memoir of Talk Radio and Literary Life” (Stanford University Press) “Spiritual Envy” (New World); “Sound Ideas” (with M.E. Sokolik/ McGraw-Hill); “Let There Be Laughter” (Harper-Collins) as well as the twenty-four lecture series in DVD, audio and book, “Short Story Masterpieces” (The Teaching Company). He has interviewed many of the world’s leading political, cultural, literary, science and technology figures, as well as major figures from the world of entertainment. He is the recipient of many awards and honors including the S.Y. Agnon Medal for Intellectual Achievement; The Eugene Block Award for Human Rights Journalism; the James Madison Freedom of Information Award; the Excellence in Journalism Award from the National Lesbian and Gay Journalists Association; Career Achievement Award from the Society of Professional Journalists and an award from the Radio and Television News Directors Association. He holds a B.A. (cum laude) and M.A. from Ohio University and a PhD from the University of Wisconsin.

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