several factors need to coincide for this wind to blow. Cold air streams from the north or north-east and meets the mountain barrier; the temperature at sea is higher than the cold air arriving from the mountain, and the air pressures differ. This air pressure and temperature difference usually arises in wintertime, when the cold polar air covers Central Europe and creates a broad area of high pressure (anticyclone), while in southern Europe the temperatures are higher and the pressure is lower. This powerful wind rushes down the steep mountain slopes and through the narrow coastal bays to the sea. The steepness of the slopes creates conditions for great speed. The wind’s movement has an extremely vertical component, which agitates the air stream. As a result, the main wind current is not unified, and the Bora blows in gusts. Strong or weak gusts blow between short or long breaks during which the wind is quiet. The Bora can last for days. Usually, it appears abruptly and dies away slowly. The speed of a strong gust of the Bora is often greater than 20 metres per second (72 kilometres per hour), which is level 9 on the Beaufort scale. Occasionally, the speed even exceeds 50 metres per second (about 180 kilometres per hour). The Bora frequently blows through the town of Senj, known also as the town of the Bora. The greatest speed measured was in 1998 at Maslenica Bridge, when 112
CROATIA AIRLINES
the wind gust speed reached 248 kilometres per hour. Some Bora gusts change intensity and direction, often blowing in a very different direction from the main air stream. Rushing towards the sea, these gusts disturb and lift the water, creating turbulent waves and scattering them into tiny drops. This spray creates an exceptional, sometimes very opaque, mist that leaves a salty layer on surfaces, which is very damaging to vegetation. As a result, those parts of the islands facing the mainland in the channel below Velebit are almost without vegetation. The largest uninhabited island in Croatia is PrviÊ, on the south side of the island of Krk. The only people living there until recently were lighthouse keepers, but the lighthouse
was automated through solar cell power, and no one lives there anymore. Statistics say that PrviÊ is Croatia’s windiest island. Other islands in the Velebit Channel met the same fate. The island of Goli, located near PrviÊ, is also uninhabited and without vegetation. This island was infamous in the times of Yugoslavia, when it was used as prison for political prisoners during the communist era. It is no wonder that the prison was built on this island, although it is not very far from the coast, for the strong current, driven by the Bora, made it impossible for the prisoners to escape. South of Goli, along the Velebit Channel, are the islands of Rab and Pag Thanks to the Bora, they are also completely barren on the north side. Communities developed on the other side, beyond the reach of the Bora. People living where the Bora is frequent need to adapt their lives to it. Since ancient times, the coastal people have defended themselves from the Bora by building special houses: rock is the basic construction material, the windows are small and not located on the north side of the house, the roof axis is from north to south, and the houses are built on special locations on the leeside and covered with strong and low roofs. The streets run from east to west so the wind does not blow directly through them. The choice of trees and crops was also dictated by their ability to resist the Bora. However, this dangerous wind has its good sides. When it blows, biometeorologic conditions are usually favourable, unlike when the Sirocco blows, and the inhabitants love it for this. Also, without the Bora there would be no famous prosciutto or cheese from the island of Pag. Its force scatters the salt over the island vegetation and, combined with aromatic herbs, gives the local lamb its fabulous taste. The local sheep cheese is also one of the best in Croatia. The sailors and fishermen there have their special way of living with this unpleasant wind. The Bora could even be responsible for the exceptional character of the local people. n