|Various possible paths for inertia currents|
There is, as with oceanography as a whole, an awful lot of maths involved with inertia current to calculate things like the centripetal force (which is essentially the Coriolis force in this case) so you can then move on to work out the period of the inertia current. I will spare you all the maths - I am currently staring at a bunch of equations that work this all out in a textbook and trust me it doesn't look very pleasant at all!!!
|Plan view demonstrating inertial motion in the|
Anyway, apparently the equations demonstrate that, in an ideal situation, the only variable affecting the period of the inertia current (basically the time taken for a water parcel to complete one circuit) is latitude so, approximately, at latitude 45 degrees, it theorectically, the period of the inertia current is 17 hours whereas, at the Equator, it becomes infinite.
Thats some of the theory, but these currents have actually be identified and observed in real life from the current measurements taken in many parts of the oceans. Here is an example of one observed in the Baltic Sea. The wind-driven current flowing to the north-north-west has been superimposed on by the inertial motion which, at this latitude, has a period of about 14 hours and, therefore, the inertia current died out after around 9 or 10 rotations.
|Plan view showing the inertial motion|
observed in the Baltic Sea
So, I think thats about it really on inertia currents - I hope some of you found it interesting!