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Tides are a complicated
phenomenon. 

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Tides in the ocean are generated
by the moon's gravitational

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pull, and they affect more than
just how much room on the beach

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there is for a chair and
umbrella. They're actually long

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period waves that move through
the oceans in response to forces

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exerted by the moon and sun,
making their way towards the

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coastlines, where they appear as
the regular rise and fall of the

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sea surface.

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And they may also help to slow
down the rate of global warming

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of the atmosphere, partially by
forming a complex system of

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underwater waves that can help
move heat into the ocean

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interior. That complex system of
waves is essentially a different

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type of tide, called Internal Tides.

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NASA can see how Internal Tides
move and flow in the ocean here.

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Across a long swath of the North
Pacific Ocean sits the Hawaiian

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Ridge, a massive underwater
structure high enough in a few

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places to reach the ocean
surface and form the islands of

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our 50th state. The tidal
currents that are generated by

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the moon's gravitation impact
the Hawaiian Ridge, causing deep

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dense water to be forced upward.
Gravity and buoyancy forces then

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tug the water down and up again,
creating oscillations. Those

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oscillations are internal waves.
But since the waves oscillate at

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the tidal period, which is the
time it takes for tides to

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complete one cycle, from high to
low, and back to high again in

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roughly 12 hours, we call them
Internal Tides.

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Once generated along the ridge,
these internal tides move away

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from it, both northwards and
southwards, and can sometimes go

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as far as thousands of miles.
underneath the surface, the

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waves can be as big as hundreds
of feet. But on the ocean

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surface, they're often only a
few inches high, barely large

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enough to notice.

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Yet instruments on satellites,
like altimeters, are capable of

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measuring those small surface
waves, and NASA can predict

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Internal Tides based on years of
compiled satellite data.

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The ocean is filled with
underwater topography, from

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mountains to ridges to trenches,
creating many sources of

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Internal Tides all over the
global ocean and giving rise to

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the many complicated patterns
seen in this visualization.

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Although Internal Tides might
seem insignificant, being only a

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few inches on the ocean surface,
they provide oceanographers with

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a unique way to map and study
the much larger internal water

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motion. That water motion and
subsequent mixing between warm

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shallow water and cold deeper
water is thought to move heat

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from global warming of Earth's
atmosphere down into the ocean interior.

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In other words, Internal Tides
are an incredibly significant

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mechanism and have a sizable
impact on the Earth's climate.