In the Northern Hemisphere, North takes it closer to the center of rotation, South takes it further away.
The train has to do something with its momentum.
Going North, as it gets closer to the center of rotation (the Earth's axis), the circumference of its circular path decreases, so its momentum makes it appear to speed up, which, because of the direction of the earth's rotation, results in a turn to the East, which is a right turn.
Going South, as it gets further from the center of rotation, the circumference of its circular path increases, so its momentum makes it appear to slow down, which, because of the direction of the earth's rotation, results in a turn to the West, which is also a right turn.
Anywhere in the Northern hemisphere, an object moving in a straight line will appear to be turned to the right as a result of the Conservation of Momentum.
We see this daily if we look at weather maps.
Although the deflection is to the right, air circulation around a low pressure area is in a counterclockwise direction.
That would seem to be a leftward shift, but it makes sense if you visualize the body of air wanting to get to the low pressure area continually being turned to the right.
It still needs to get to the low pressure area, tries to get there, and continues to be turned right.
Hopefully anyone studying this can see how that makes the air travel in a counterclockwise, or left spiral.
I originally learned about this in a weather class I took while training to be an Air Traffic Controller.
It didn't really click for me, though, until I studied helicopter aerodynamics as a helicopter mechanic.
The tips of a helicopter's rotor blades travel across a spherical section, as described by the length of the blades and the amount they flap up and down. As they flap up, they act like a Northbound train, as they flap down, they act like a Southbound train.
My wife really enjoys it when I explain this to people at parties. |
