CNN The Wonder List With Bill Weir April 6, 2015 02:16:00
Watch for other famous phenomenon which begins with that siren. [ humming siren ] it is the sound of an approaching aqua alta, high water propelled by moon and wind. you see a full moon brings higher tides, and when the sir oko winds are blowing up the back of the italian boot, adriatic seawater comes rushing through the three inlets of the venice lagoon. it's predictable, so three hours before the liquid lifts comes that haunting alarm. one tone means the water will reach 110 centimeters above normal. two tones, 120 and so on. today it will top 130, 4'3" above normal. higher parts of the city...
Source: archive.org