The Mediterranean Sea

The Mediterranean is a relatively small sea. It connects three continents: Asia, Africa, and Europe. It covers 2.5 million square kilometers. The area of the Mediterranean is only 3% of the area of all the seas and oceans in the world, which collectively comprise 71% of the area of the Earth.

Unlike the oceans, which are open, the Mediterranean is closed on its eastern side. On the west, it connects with the Atlantic Ocean through the Straits of Gibraltar. In the northeast it connects with the Black Sea through the Dardanelles. In the southeast it connects to the Red Sea through the Suez Canal.

Along the 46,000 kilometer coastline 150 million people live. Twenty-one nations have coasts on the Mediterranean. In Asia they are: Syria, Lebanon, and Israel. In (southern) Europe they are: Spain, France, Monaco, Italy, Greece, Turkey, Slovenia, Croatia, Bosnia-Herzegovina, Montenegro, and Albania. In (north) Africa they are: Morocco, Algeria, Tunisia, Libya, and Egypt. Island nations wholly within the Mediterranean are Cyprus and Malta.

Israel has 150 kilometers of coastline on the Mediterranean. Of those, fifty are closed to the public. They are used as ports, power stations, and infrastructure and for military and security needs. Bathing beaches are so designated only where there are lifeguards and patrol boats.

The climate throughout the Mediterranean Basin is relatively the same although temperatures in the east are warmer than those in the west. The temperature of the water at the surface has risen in recent years because of the greenhouse effect. Because the Mediterranean is a relatively small sea, it warms much faster than the larger bodies of water. Off the coasts of Israel and Egypt, the sea warms to 31° Celsius in the summer and cools to 16° Celsius in the winter. In the western portion of the Mediterranean, summer water temperature reaches 26° Celsius and in the winter drops to 11° Celsius.

The western Mediterranean is also slightly less salty than in the east, 3.5% to 3.9%.

Jellyfish arrive at Israeli beaches in the spring and summer when water temperature is 26° Celsius and above. The rhopilema nomadica began arriving at Israeli beaches in the late 1980's. This is a toxic species of jellyfish called the thread-like jellyfish in Hebrew. It is somewhat circular; its diameter ranges from 35-50 cm. In the past three decades, as the sea has warmed, the number of jellyfish has risen and now massive swarms of jellyfish reach Israel in the spring. In the summer of 2010 the beaches, primarily in the south, were inundated by millions of jellyfish. Jellyfish can travel great distances depending in the winds and sea currents. Several theories have been proposed for the large increase in the jellyfish population: the greenhouse effect, pollution of the waters of the Mediterranean, and deficiency of other fish in the sea.

There are two main currents in the Mediterranean. The Western Current begins at the Straits of Gibraltar, follows the North African coast, turns north to Corsica, then along the Southern European coast past the Balearic Islands, and back to Gibraltar. The Eastern Current is slower than the western. It flows counter-clockwise along the coasts of Libya, Egypt, Israel, Lebanon, Syria, Turkey, and Greece.

The climate in the eastern Mediterranean Basin is characterized by hot, dry summers and cold, rainy winters. The summer coastal areas are extremely muggy in the summer but temperatures there are milder than inland. Winter temperatures near the coast are also milder than inland.

Two major weather systems affect the Mediterranean Basin: cold weather systems over Europe and the subtropical high over the desert areas to the south. In the summer, the subtropical high spreads northward to include southern Europe, causing hot, dry weather. This is pronounced in Israel. The subtropical high retreats in the fall allowing cold weather systems accompanied by rain to enter the Mediterranean Basin. High altitude troughs bring rain to Israel. Because of global warming, the subtropical high has strengthened. It arrives sooner in the spring and leaves later in the autumn. The result has been warmer temperatures and less precipitation throughout the Mediterranean Basin. The Mediterranean Sea is relatively small, so, when rain-bearing systems do develop they are shallower than systems over the open oceans where great storms such as hurricanes and typhoons develop. The geography of the Mediterranean doesn't allow such storms to develop. The rise in water temperature has led to a rise in surface temperature along the coasts. One degree increase in water temperature translates into a two-degree rise in air temperature. The rise in water temperature is expected to bring increased autumn rainfall to Israel's coastal areas.

Solar Radiation, UV, on Israel's Beaches

Israel's location at 29-33° north latitude allows many hours of sunlight and strong ultra-violet (UV) radiation, especially from May to October. The amount of UV radiation is influenced by the angle at which the radiation reaches the Earth, cloud cover, and air pollution. Beach to beach, there is little difference in the amount of UV that reaches Israel's beaches on clear summer days. There is much greater difference in the amounts of UV that reach different coastal locations in Israel in the winter because cloud cover in the north and center is much greater than in the south where, even in winter, the skies are usually clear. The amount of UV that reaches the Dead Sea, at an elevation of 424 meters below sea level, is surprisingly similar to the amount that reaches the sea-level coasts. There is, in fact, some increased filtering of UV at the Dead Sea but it is insignificant. Ultra-violet light is measured on an ascending scale from 0 to 13. From 0-5 the amount of UV is considered low to moderate and not dangerous; from 6-8 it is considered high and dangerous to exposure; 9-10 is very high; and 11-13 is extremely dangerous. In the summer, the greatest amount of UV reaches Israel between 11:00 A.M. and 3:00 P.M. It is important to note that exposure to UV also takes place in shaded areas. The safest time to sit in the sun and to suntan is between 7:00 and 10:00 A.M. and between 4:00 and 7:00 P.M. At these times the UV will be the least dangerous. Over-exposure to UV can result in skin reddening, blistering, sunburn, and even skin cancer. It is also important to be aware that UV exposure increases at the beach because of reflection from the sea and the sand.