  The details of trajectories of charged particles become increasingly
important for proper understanding of processes of formation of radiation in
strong and curved magnetic fields. Because of damping of the perpendicular
component of motion, the particle's pitch angle could be decreased by many
orders of magnitude leading to the change of the radiation regime -- from
synchrotron to the curvature mode. To explore the character of this transition,
we solve numerically the equations of motion of a test particle in a dipole
magnetic field, and calculate the energy spectrum of magnetic bremsstrahlung
self-consistently, i.e. without a priori assumptions on the radiation regime.
In this way we can trace the transitions between the synchrotron and curvature
regimes, as well as study the third (intermediate or the so-called
synchro-curvature) regime. We briefly discuss three interesting astrophysical
scenarios, the radiation of electrons in the pulsar magnetosphere in the polar
cap and outer gap models, as well as the radiation of ultrahigh energy protons
in the magnetosphere of a massive black hole, and demonstrate that in these
models the synchrotron, synchro-curvature and curvature regimes can be realized
with quite different relative contributions to the total emission.
