Question submitted by Sean (Kamloops)
In physics, the Coriolis effect is an apparent deflection of moving objects when they are viewed from a rotating frame of reference.
In a meteorological frame of reference, as air moves from high to low pressure in the northern hemisphere, it is deflected to the right by the Coriolis force. In the southern hemisphere, air moving from high to low pressure is deflected to the left by the Coriolis force.
The amount of deflection the air makes is directly related to both the speed at which the air is moving and its latitude. Therefore, slowly blowing winds will be deflected only a small amount, while stronger winds will be deflected more. Likewise, winds blowing closer to the poles will be deflected more than winds at the same speed closer to the equator. The Coriolis force is zero right at the equator.
When talking about a fluid in a toilet bowl however, the Coriolis force is completely overcome by the local mechanisms that start the water swirling in the bowl. It is a common misconception that water will flow down a drain or a toilet in a direction depending purely on the Coriolis force.