  We explore theoretically the magnetoresistvity of three-dimensional Weyl and
Dirac semimetals in transversal magnetic fields within two alternative models
of disorder: (i) short-range impurities and (ii) charged (Coulomb) impurities.
Impurity scattering is treated using the self-consistent Born approximation. We
find that an unusual broadening of Landau levels leads to a variety of regimes
of the resistivity scaling in the temperature-magnetic field plane. In
particular, the magnetoresitance is non-monotonous for the white-noise disorder
model. For $H\to 0$ the magnetoresistance for short-range impurities vanishes
in a non-analytic way as $H^{1/3}$. In the limits of strongest magnetic fields
$H$, the magnetoresistivity vanishes as $1/H$ for pointlike impurities, while
it is linear and positive in the model with Coulomb impurities.
