Rembrandt lighting is named after Rembrandt the Dutch painter. The effect can be created using a single light positioned 1 meter away from the model. If the light is too far away the strong atmospheric shadows are not as defined. The position of the light is placed higher than the model and approximately 45 degrees to the left or right of the face when looking straight at the face.
The Rembrandt lighting effect can also be created with two lights, the main lighting is above the face 30-80 degrees there is second light on either the left or right side of the face 25-60 degrees. This gives atmosphere and strong shadows on the face light and shadow patterns characterized by a small triangle of light that appears under the eye on the shadow side of the face, along with a nose shadow that nearly extends to the corner of the mouth.
My portrait demonstrating the Rembrandt lighting was taken in the studio using a single light source with a Nikon D3100 camera, ISO-3200, aperture F-stop f7.1, Exposure time 1/80 second, 55mm lens.