William M Connolley is contradicting himself I am copying this from a section higher up on this same page Talk 19 51 33 2005 07 31 UTC Now on with the explanation The Coriolis effect is a change of coordinates force and thus bears intriguing similarities with gravity whether this means anything or not is unclear When you move from one coordinate system to one that is rotating with respect to the first then the equations of motion for a particle acquire an extra term the coriolis term and one other of second order in omega but we ll neglect that So if you wish to formulate the equations of motion for air on the surface of the earth it is natural do to it in a coordinate system stationary wrt the earths surface in that case you end up with a coriolis force You could if you wished write the equations in a system non rotating wrt the fixed stars perhaps ignoring the rotation of the earth round the sun In this system there would be no coriolis effect and hence no coriolis force However there would be a very rapidly moving lower boundary to account for and this would be deeply inconvenient since the coriolis term is easy to incorporate there is no particular reason to do this But this is only the coordinate system in which you choose to write your equations It has no effect on the physics and cyclones continue to rotate no matter which system you describe them in The coriolis effect is not physics it is kinematics 19 51 33 2005 07 31 UTC end of copied section William M Connolley is simultaneously saying that the coriolis effect is physics and that it isn t An article about the coriolis effect should explain the following If hypotherically speaking a low pressure area would form on a non rotating planet then the air would flow towards the low pressure area and the pressure gradient would very rapidly be leveled But that is not what is happening on Earth On Earth air starts flowing around a low pressure area amazingly it tends strongly to flow perpendigular to the pressure gradient and it can take weeks for a low pressure area to become leveled again So there must be a physical mechanism that performs a restructuring of the direction of wind flow A general coordinate transform transforms the entire picture in one go if you employ a coordinate transformaton to a rotating coordinate system on say a large grid then the grid will turns around as a whole with the whole picture remaining in a fixed form That is not what happens in the atmosphere If you let go lots of weather balloons in the area of a low pressure area forming then over time the positions of the balloons in the circling winds will be thoroughly mixed The more central parts of the system rotate faster William says that the coriolis effect is to be understood as purely a cosmetic change a coordinate transformation that does not alter the physics taking place But Willam also believes the following from The Coriolis force plays a strong role in weather patterns where it affects prevailing winds and the rotation of storms as well as in the direction of ocean currents Above the atmospheric boundary layer friction plays a relatively minor role as air parcels move mostly parallel to each other Here an approximate balance between pressure gradient force and Coriolis force exists causing the geostrophic wind which is the wind effected by these two forces only to blow along isobars along lines of constant geopotential height to be precise Thus a northern hemispheric low pressure system rotates in a counterclockwise direction while northern hemispheric high pressure systems or cyclones on the southern hemisphere rotate in a clockwise manner as described by Buys Ballot s law This is why I recognize that there are two contexts that both called coriolis effect One context is about physical mechanisms the other is about coordinate transformation Talk