aja jooksul sademes kulgevad muutused (kristallide kasv, veesisalduse vähenemine, eripinna suurenemine jne), mis üldiselt parandavad sademe filtreeruvust, the time-dependent change of those properties of a precipitate, e.g. loss of water, growth of crystals,  recrystallization, decrease of the specific surface, loss of coprecipitated substances, which generally improve the filtering properties