  Long length vacuum oscillations solution of the solar neutrino problem is
discussed. We show that there is a strict correlation between a distortion of
the neutrino energy spectrum and an amplitude of seasonal variations of the
neutrino flux. The slope parameter which characterizes a distortion of the
recoil electron energy spectrum in the Super-Kamiokande experiment and the
seasonal asymmetry of the signal have been calculated in a wide range of
oscillation parameters. The correlation of the slope and asymmetry gives
crucial criteria for identification or exclusion of this solution. For the
positive slope indicated by preliminary Super-Kamiokande data we predict (40 -
60) % enhancement of the seasonal variations.
