Baer's Law


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Baer’s Law

 

a thesis that explains the reason for the erosion of the banks of rivers which flow in the direction of the meridians; in the northern hemisphere the right banks erode, and in the southern, the left. In 1857, Karl Maksimovich Baer (also Karl Ernst von Baer) explained that phenomenon by the influence of the earth’s rotation. It is known that a body moving forward in a revolving system experiences Coriolis acceleration. In the case of the movement of water and air currents with a velocity v on the earth’s surface at latitude φ, this acceleration equals 2ων sin φ (where ω equals the angular velocity of the earth’s rotation). This is directed to the right in relation to the speed of movement in the northern hemisphere and to the left in the southern.

At the equator, Coriolis acceleration is equal to zero, and it is greatest at the poles. Thus Baer’s law is more strongly apparent in middle and high latitudes. In relation to air currents (winds) in free atmosphere, the effect of this factor has been well studied, just as it has in relation to sea and ocean currents. The case of channeled currents, to which Baer’s law relates, is more complicated because the shores hinder the sideways movement of the current; this leads to the undercutting of the corresponding shore. The effect of Baer’s law is directly proportional to the mass of the moving water and is clearly noticeable only in the valleys of large rivers, being barely apparent in small rivers. In addition, the erosion of the corresponding shore is often concealed by the basic slope of the locale, the geological structure of the valley, and other factors. The structure of the banks of the Dnieper, Don, Volga, Ob’, Irtysh, and Lena rivers serves as an example of Baer’s law. The Danube and the Nile also have high right banks and low left banks along most of their course. In the southern hemisphere, there are rivers with steep left banks in New Zealand and South America.