Причина:https://ru.wikipedia.org/wiki/%D0%92%D1%80%D0%BE%D0%B6%D0%B4%D1%91%D0%BD%D0%BD%D0%B0%D1%8F_%D0%B1%D0%B8%D1%81%D0%B5%D0%BA%D1%81%D1%83%D0%B0%D0%BB%D1%8C%D0%BD%D0%BE%D1%81%D1%82%D1%8C