There are three types of polarization for all transmitted RF energy (cell signals) - vertical, horizontal and circular.
The type of polarization is dictated by the transmitting antenna; virtually all cell towers use vertical dipoles. This is why we specify that all Digital Antenna omni-directional antennas must be vertically positioned.
All cellular signals are vertically polarized. However, over distance they do rotate in space, at least theoretically.
The cell tower sends the cell signal in a vertical pattern. Because the actual path of the signal from the cell tower to the outside antenna can vary, including multiple bounces and reflections between the tower and the antenna, it would be impossible to know the exact relation of the polarization being received.
An antenna should be installed with the proper polarization according to the instructions. In general, the signal should improve with proper polarization since microwave (cell) signals are very sensitive to it.