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- Hey there, I'm Josh Clark
and in this Brain Stuff
I explain to you how the tides work.
Have you ever seen somebody
buried up to their neck
in sand on the beach and
then the tide slowly comes in
and they drown and wondered,
I wonder how tides work?
Well, next time you'll
know and you can explain it
to that person as they wait to die.
We need to be very careful here because
as French astronomer
Francois Arago once said,
studying the tides is the
tomb of human curiosity
which means, it can break
your brain as you'll see.
There's a lot of factors
involved in creating the tides
here on earth but the big
three are the moon, the sun
and the earth.
The gravitational pull of
all three of those bodies
interacting creates the tides.
The biggest factor actually is the moon.
It exerts about 2.2 times
more power on the tides
than the sun does.
So for once, the moon
gets to one up the sun.
It's kind of a big deal to it.
Imagine for our purposes
the earth is right here
and the moon is directly above it.
Now, they exert a gravitational
pull on one another
and since on the earth
most things are pinned down
we have shoes, buildings have foundations,
stuff stays in place.
But, the oceans, being
literally fluid, actually can be
pulled toward the moon and
this is what creates the tide.
The moon's here, it's pulling
on the ocean at the top
of the earth, creating
a high tide on the top.
And on the bottom, another
high tide is created,
because the earth itself
is pulled toward the moon
even though the ocean's down
here have less gravitational
pull exerted on them, being
farthest away from the moon.
So on the top and bottom,
you have high tide,
cause of the tidal bulges
and on the sides that are
right angles to the moon,
you have low tide cause the
ocean's stretched thin over
the surface of the earth.
Pretty crazy, huh?
So like I said, the sun
also exerts an influence
on the tides, but it's less
pronounced than the moons.
See, it actually enhances or
diminishes the gravitational
pull of the moon here on earth.
When the sun and the moon
are in alignment, the sun
enhances the moons
gravitational pull creating
higher tides than normal.
They're called spring tides
and they happen on a full moon
or a new moon.
Now when the sun and the
moon are at right angles
to one another, with the
earth right about here,
the sun diminishes the
gravitational pull of the moon
on earth creating lower
than normal high tides,
also called neap tides.
These happen on the quarter moons.
Because the earth and the
moon are constantly moving,
and moving around one another,
there's a constant movement
from high tide to low tide.
Twice a day, you get a
high tide in most places,
usually once every 12
hours and 25 minutes.
But, this can vary and some
places only see a high tide
once every 24 hours.
Those are called diurnal tides.
So this is a daily occurrence,
actually twice daily
in most places.
But tidal waves, even though
they have the word tide
in them, pretty much, but
without the E, they're not
related to this
gravitational push and pull.
They're usually the result of earthquakes.
So that's tides.
Hopefully we avoided that
tomb of human curiosity
and you guys get it.
If not, going back and watching it again,
there's no shame in that.
It's pretty heavy stuff.
If you like this video, let us know.
Leave us a comment below
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