xkcd #3135: Sea Level

Title text:

They're up there with coral islands, lightning, and caterpillars turning into butterflies.

Transcript:

Transcript will show once it’s been added to explainxkcd.com

Source: https://xkcd.com/3135/

explainxkcd for #3135

They're up there with coral islands, lightning, and caterpillars turning into butterflies.
you are viewing a single comment's thread
view the rest of the comments
[–] 50 points 1 year ago (11 children)

Been trying to learn about the tides around here so I can tell what I'm seeing on the water. Imagine my joy when I found a Casio, which I collect, with tide and moon phase indicators!

And that's when I learned the Gulf Coast is strange, has diurnal tides (twice a day) the watch can't predict. Took me an hour and a half to figure out it would never function. The moon phase works!

  • source
  • hideshow 11 child comments
  • [–] 14 points 1 year ago (3 children)

    the Gulf Coast is strange, has diurnal tides (twice a day)

    Diurnal tides are once a day (semidiurnal is twice a day). By the Gulf Coast, I guess you must mean the Gulf of Mexico. I'm living on the other side of the world in the other diurnal region, so I assume our tides are synchronised!

  • source
  • parent
  • hideshow 3 child comments
  • [–] 9 points 1 year ago (1 child)

    Tidal prediction requires a harmonic analysis of observed tides, and its location specific. Not sure how a watch is supposed to do that other than holding a database of tidal coefficients.

    This video contains a lot of interesting history of tidal analysis and prediction:

    https://youtu.be/IgF3OX8nT0w

  • source
  • parent
  • hideshow 1 child comment