An international blackout across Spain, Portugal and the south of France left millions without electricity early this week , with experts still unsure what caused the outage. Portugal's national electricity network initially blamed the event of a rare atmospheric phenomenon known as an "induced atmospheric vibration," although they later refuted this explanation. Induced atmospheric vibrations are unusual oscillations in high voltage power lines that occur when an area experiences extreme changes in temperature. While it has not been confirmed whether this particular outage was caused by such an event, experts have warned that the extreme temperature fluctuations that cause this...