Aurora ⇔ Temperature : no relation, but...
   * cold   ~ often clear sky = can see
   * warm ~ often cloudy     = cannot
Aurora ⇔ Season : some relation, but...
   * solstice = less, but long night
   * equinox = more, but short night
      Ÿ same chance to see aurora 
      Ÿ other factors (weather) determine 
Sound of Aurora ? nobody knows.