Tag Archives: coriolis

Earth’s atmosphere and oceans in motion

Two mesmerizing visualizations of dynamics on planet Earth with scientific data have recently been made public. The first shows ocean currents measured over a two-year interval, and the second traces atmospheric winds in real time.

Together they illustrate the main features of dynamics on a rotating planets, the Coriolis effect.

NASA Ocean currents
Still from the movie of ocean currents over the 2005-2007 period. Notice how the gap betwen Africa and Madagascar, combined with the Coriolis effect, generates a train of vortices drifting past the Cape of Good Hope.

The movie of ocean currents, produced by NASA, is available on this site or or as a youtube movie .

The real time flow of winds can be accessed here.

Screen shot 2014-05-11 at 11.07.56
Still from the movie of wind motions.

 

Note in the first image how the ocean currents share a similar “typical radius”, defining the size of the vortices, and the length of the loops in the snaky flow. Wind system also have a characteristic size in the second image, which is much larger.

The size of the loops and swirls is defined by the Coriolis effect, that makes currents on a rotating sphere veer aside.  The faster the rotation, the smaller the swirls. And the heavier and slower the fluid, the smaller the swirl, hence the difference between ocean currents and atmospheric winds.

Some planetary atmosphere behave more like Earth’s ocean than its air. For instance, long-lasting vortices form in Jupiter’s atmosphere, analogous to loops in ocean currents.