Coriolis Effect

Going Down  On the Earth “down” includes centrifugal effects. Objects at restObjects at rest Assume effective gravityAssume effective gravity Local coordinates match “down”Local coordinates match “down”  Select 3-axis opposite to down. North in plane with North in plane with  East as 1-axisEast as 1-axis

Local Velocity  The angular velocity of the Earth can be expressed in local coordinates.  The local velocity is used to get the Coriolis force. e2e2 e3e3 

Deflection  VelocityNorthern Southern Hemisphere  NorthEastWest  SouthWestEast  EastSouth and UpNorth and Up  WestNorth and DownSouth and Down  UpWestWest  DownEastEast

Cyclone  In the absence of rotation air would move from high to low pressure. Straight line wind  The Coriolis force causes wind to turn. Friction causes equilibrium Circular pattern L L

Global Flow  The general wind circulation is a result of Coriolis forces.  Equatorial warm air rises and turns east. Replacing cold air turns westReplacing cold air turns west Trade windsTrade winds  Northbound air here turns east – prevailing wind.

Pendulum Swing  A pendulum has a local velocity. Measure displacement from equilibrium.  Coriolis force causes a deflection. Select frame that rotates  F with deflection. F cor

Foucault Pendulum  The new rotation vector is up in the local system. Related to colatitudeRelated to colatitude  Select the local rotation to cancel the Earth’s rotation. Pendulum moves in a turning planePendulum moves in a turning plane Turning represents precessionTurning represents precession