With Spherical Mapping the light is wrapped around the lighting sphere. In this mode the width of the light should be set to 100 so that the lighting is wrapped around the sphere. Values less than 100 produce largely undesirable effects. Spherical mapping is best used for full canvas gradients or full canvas environments. In the example below, varying the longitude and latitude essentially rotates the location of the 'North Pole' relative to the lighting sphere.
Tilting the Background Image
Another good use of spherical mapping is for tilting HDRI maps. Remember that wherever you click on the canvas to position this mapping, the north pole of the spherical image is moved to that location, as shown by the cross in the images below.
Transform Settings for Spherical mapping
In this mapping mode lights are placed by their top edge. Therefore the Latitude and Longitude settings relate to this location.
The latitude defines the vertical position on the canvas. Values range from -90 (north pole) to 90 (south pole). A value of zero will position the light at the equator.
This determines the horizontal position of the light on the canvas. Values range from 0 to 360 degrees around the virtual sphere.
This is the horizontal dimension of the light expressed as a % of the sphere. For this mapping, it is advised to keep this at 100%
This is the vertical dimension of the light expressed as a % of the sphere. For a full canvas gradient or image, this should also be 100%.
Changing the rotation in this mapping will move the content left to right around the north pole. Here is an example: