When sailors cross the Equator, they often celebrate this occasion with some kind of an initation rite for Neptune, the ancient Roman god of the sea. Sailors who have already crossed the Equator are nicknamed Shellbacks, often referred to as Sons of Neptune; those who have not are nicknamed Pollywogs.
As far as I know, no such thing exists for travellers crossing the equator by airplane. So, I will have to invent a ceremony by myself in honour of the weather gods. After all, They are the one's who have mapped out this adventure for me ;-)
For a European weather forecaster as myself, it's so obvious that air is always flowing counter-clockwise around a low and clockwise around a high-pressure area. After crossing the Equator however, this general rule will no longer be true, because at the Southern Hemisphere, everything is turning the other way around.
This can be explained with the Coriolis effect. That's the apparent deflection of moving objects when the motion is described relative to a rotating reference frame. In a reference frame with clockwise rotation, the deflection is to the left of the motion of the object; in one with counter-clockwise rotation, the deflection is to the right. Although recognized previously by others, the mathematical expression for the Coriolis force appeared in an 1835 paper by French scientist Gaspard-Gustave Coriolis.
Coriolis did experiments on friction and hydraulics and he worked on the effects of kinetic energy on the principle of kinetic energy in the relative motion in machines. Being a fanatic pool player, he began to wonder how the balls would move on a rotating table. And that off course, was just the start of the mathematical expression of the Coriolis effect.
I found a nice Youtube-video, that well explains the Coriolis effect. Enjoy it!