CRUISING GREECE: AN UNFORGETTABLE JOURNEY FROM ATHENS TO CHAKIDA, GREECE
CRUISING GREECE:
AN UNFORGETTABLE JOURNEY FROM ATHENS TO CHALKIDA, GREECE
Chalkida, (is) a city perched amphitheatrically in central Evia.ย Chalkida straddles the beguiling Strait of Evripos, bridging the coast of Evia and Boeotian mainland. A modern metropolis pulsating with history, Chalkida embraces its maritime heritage and hospitable spirit. The city's allure lies in its unique dance with natureโthe captivating tidal spectacle of the Gulf of Evia.
The one thing Chalkida is world-famous for is the peculiar tidal currents that flow interchangeably north-to-south and south-to-north through the Euripus Strait between the island and the mainland. It is this phenomenon that has given the city the nickname: Crazy Waters.
Reversing tidal currents are caused by the moonโs gravity and occur in all straits worldwide, but they are mostly imperceptible by the human senses. It is the distinct geography of Chalkidaโs straitโits double-funnel shape among other factorsโthat make the local currents particularly strong.
The flow peaks at an astounding speed of 12 km per hour, which, for context, is comparable to torrents during floods. For most of the month, the current changes direction about every six hours with a clockโs regularity. But for a few days around the half-moons, it loses its pattern altogether, moving back and forth in chaotic ways.
The 38-meters-wide strait is spanned by an 8-meter-tall bridge, which, constructed in 1963, is the latest of a long succession of bridges dating back to antiquity. The bridge is withdrawn usually once every evening to allow for large vessels to traverse the strait. Given the powerful stream with its notorious vortexes, it requires skillful maneuvering to sail through. It is quite an impressive spectacle to behold. Due to the unpredictability of the currents, the bridgeโs opening times are not standard. Estimations are stated on a screen on the spot and live views of the bridge can be seen here.
If youโre now thinking that itโd be great fun to jump from the bridge, you are totally right. But it is unfortunately illegal. However, this detail wouldnโt stop us when we were kidsโฆ Free-falling for a short distance, weโd then be engulfed and drifted around by the currents, losing every sense of direction within this dark whirlpool of pressing liquid, for up to half a minute. By the time weโd reach the surface, we could be more than 50 meters away from the bridge, laughing and waving at the coastguards who were always a little too late to stop us.
SVย SMALL WORLD III ๐ป๐ฎ Karen & Darren -ย Bristol 47
THANK YOU FOR SHARING YOUR ADVENTURE
STRAIGHT OF GIBRALTAR
STRAIGHT OF GIBRALTAR
Over 100,000 ships transit through Gibraltar every year
Density of seawater in the Strait of Gibraltar One of the unique features of the Strait of Gibraltar is the inflow and outflow of the Medย which consists of layers of water with different salinity (salinity). Atlantic water is less saline and less concentrated than Mediterranean water, and flows eastward into the Mediterranean through straits as a surface layer, flowing at a speed of 2 to 3 knots at a depth of about 125 m. In contrast, heavier, cooler, and saltier water flows westward into the Atlantic Ocean. Depending on the phase of the tide, the currents flow eastward faster or slower.
Tides in the Strait of Gibraltar โย
A very distinctive feature of the Strait of Gibraltar is the continuous evaporation of water. Vertical water height in the Mediterranean Sea decreases by almost 1 meter every year. About 6.5+ million years ago, the general shape of the Mediterranean base was similar to what it is today. The movement of the plates cut off the flow of water from ocean to ocean, completely evaporating the area. But about 5+ million years ago, the plates moved again and the straits opened, allowing large amounts of water to flow out of the ocean and refill the Mediterranean basin. This evaporation continues today, and it is estimated that if the strait were to close at current high sea levels, the basin would evaporate again. Backwash and Internal Waves Adding another challenging piece to the tidal puzzle that shapes the Strait of Gibraltar near the African continent are the often narrow two-knot backwashes that interact with the Caminal Stile (the shallowest part of the strait) and cause internally generated waves. As stated by NASA; "The waves are generated when daily tidal pulses flow through the shallow Caminal Stile near Gibraltar. They flow eastward and break up the coastal topography. They can be traced up to 90 nm, and in some cases produce interference patterns due to refracted waves
Internal waves are vertical movements between two layers and can have displacements of over 100 m with wavelengths of 1-3 nm. They are so noticeable as surface wave patterns that sunlight is carefully scattered by the water surface
Alboran Gyre
As the upper-level flow pours into the Mediterranean, the Coriolis force (an effect of the earth's rotation) causes it to form a large clockwise eddy (gyre) off the North African coast called the Alboran Gyre. A smaller weak anti-clockwise eddy forms to the North. Countercurrents (westward direcction) can be seen close inshore along both shores, particularly near headlands that project into the current.
The western end of the Mediterranean, akaย Alboran Sea, is the habitat for aย largest population of dolphins in the western Mediterranean
A layer of outward-flowing dense water stays deep after exiting the Mediterranean and forms a ribbon extending along the Spanish and Portuguese coasts at about 1000m depth.
Modelling the Strait of Gibraltar
WINDS
CURRENTS
SWELL AND WAVESย
