The loss of energy from a wavefront as a consequence of geometrical spreading, observable as a decrease in waveamplitude. Spherical divergence decreases energy with the square of the distance. Cylindrical divergence decreases energy with the distance.

In mathematics, a process in which a sequence of numbers does not tend to a fixed limit (the opposite of convergence). Divergence is a mathematical property of a vector field that is a local measure of its rate of spreading.

In Cartesian coordinates, divergence is the sum of the partial derivatives of each component of the vector field with respect to the corresponding spatial coordinate: