Here is 2 simple lighting styles which are commonly used by photographers in portraiture photography. One of it is open loop lighting and the other is close loop lighting.
"Open loop" lighting is obtained by using the short lighting method. The shadow formed by the nose does not 'join' to the shadow on the side of the face that faces the camera. You can create the same effect if you increase the angle of the light which is coming from the side of the face which is not towards the camera. Below is an example of how open loop lighting looks like:
Did you see that the shadow of the nose does not connect to the shadow at the other side of the cheek? But after you add the softbox down, the effect becomes not so obvious.
Close loop/ Rembrandt Lighting
Rembrandt lighting is obtained by combining short lighting and butterfly lighting. The main light is positioned high and on the side of the face that is away from the camera. This technique produces an illuminated triangle on the cheek closest to the camera. The triangle will illuminate just under the eye and not below the nose.
By looking at the picture above, can you get a glimpse of what I'm trying to say? This effect can be easily obtained when you decrease the angle of the light coming from the face that is away from the camera. The shadow will eventually do a close loop.