  The solar activity in the current, that is, the 24-th, sunspot cycle is
analyzed. Cyclic variations in the sunspot number (SSN) and radiation fluxes in
various spectral ranges have been estimated in comparison with the general
level of the solar radiation, which is traditionally determined by the radio
emission flux $F_ {10.7} $ at a wavelength of 10.7 cm (2.8 GHz). The
comparative analysis of the variations in the solar constant and solar indices
in the UV range, which are important for modeling the state of the Earth's
atmosphere, in the weak 24th cycle and strong 22nd and 23rd cycles showed
relative differences in the amplitudes of variations from the minimum to the
maximum of the cycle. The influence of the hysteresis effect between the
activity indices and $F_ {10.7} $ in the 24-th cycle, which is considered here,
makes it possible to refine the forecast of the UV indices and solar constant
depending on the quadratic regression coefficients that associate the solar
indices with $F_ {10.7} $ depending on the phase of the cycle.
