Showing posts with label Sardinia. Show all posts
Showing posts with label Sardinia. Show all posts

Monday, October 1, 2018

Medicanes

Mediterranean cyclones are called Medicanes from the words Mediterranean and Hurricanes.  They usually form in the sea between Spain, Sardinia and Corsica or in the Ionian Sea. Medicanes usually happen in the fall and winter and move from west to east.  
Medicanes are rare phenomena and are similar with the tropical cyclones but are weaker because the Mediterranean Sea is smaller comparing to the oceans and her waters are not as warm. 
Although not as ferocious as their tropical cousins Medicanes have a center, have very strong winds in their periphery, causing huge waves and torrential rainfalls. 
Medicanes frequency is 1-2 per year.  Greece’s last Medicane was in 1995. This time the cyclone skirted the south coast of Peloponnese and reached Athens on Saturday September 29, 2018.
The strong winds uproot trees and down power lines and cause all kind of property destruction. 
Swollen rivers take cars parked near their banks in their turbulent waters downstream.  
The strong winds and waves result in sinking of boats even in harbors.
Although the advice to people in regions involved by hurricanes to move inland and away from the coasts some elect to ignore such warnings and go to the shore to see the large waves and feel the strong winds.
Tourists in the vicinity of the Acropolis of Athens look happy even if the gusty winds will destroy their umbrellas.

Wednesday, December 16, 2015

Navigation by the Ancients

Ancient mariners knew that the sea is large and getting lost was easy especially if someone ventured out far from the coast.  So how did ancient navigators, like the Polynesians, found their way and guided their boats on the intended course across vast oceans to safe harbors?    
Ancient navigators used local knowledge and lore to guide them.  Such knowledge was amassed from fanciful narrations of sailors who upon their return spoke about distant lands, monsters and of people they met.    
The logbooks and diaries aboard a sailboat recorded everything from how long it took to travel between two sites, and the routes they took were drawn on extremely valuable and often illustrated maps.  A reliable method to fixing one’s position was and still is by monitoring depth soundings. Herodotus in the fourth century BC said “when you get 11 fathoms on the lead you are one day’s distance from Alexandria”.  We used depth soundings in our crossing of the strait of Bonifacio when we got close to the island of Magdalena north of Sardinia.
In antiquity as today sailors were familiar with seasonal variations, prevailing winds and wave patterns of the seas near the lands they lived.  They Minoans were pioneers of long-distance travel as seen in the sixteen-century BC mural found in the island of Santorini.  They took advantage of the strong northerly wind Meltemi that blows daily in the Aegean during the summer months that propelled them to Crete and as far as Egypt.     
The first seafarers followed the land or sailed to nearby islands thus navigators depended on coastal navigation.  The most celebrated of the Ancient Sailors was the Greek Pytheas who left from Marseille in 325 BC sailed to the British Isles, Scandinavia, Baltic Sea and Thule that it was likely Iceland or even North America.  
Ptolemy a second century Greek mathematician, astronomer and geographer assigned coordinates of latitude and longitude to as many as 8,000 geographic locations.  His atlas was carved initially on wooden blocks.  While a recent publication of his work was on the 1482 edition of Geographia.