Abstract
An attempt was wade to clarify the synoptic and local climatological features of Bora in Yugoslavia. First macro-climatological conditions of Bora regions together with the other strong local winds in winter in the Northern Hemisphere were considered in relation to the surface and the 500-mb level pressure patterns. The result revealed that they situate at the margin of the Eurasian high at the surface level or under the climatic troughs at the 500-mb level in winter, where cold air advection or cold air outflows tend to occur.
Then, statistical aspects of Bora were summarized as follows: 1) Reaching higher (over 15 m/s) wind velocity, they occur frequently in winter. 2) Air temperature is lower than 0°C in January and February. 3) Relative humidity is lower than 40% in the case of anticyclonic Bora. 4) The stronger Bora blows normally in nighttime and reaches its maximum in the early morning during 5—8 AM. 5) They continue 12—20 hours in most cases. And, 6) In the exceptional cases, Bora prevails longer than 10 days.
The local climatological investigations came to the following conclusion: Sudden, short time temperature rise is seen usually in the beginning of Bora. During the Bora period, relative humidity dropps occasionally very low in association with the anticyclonic situation. The stronger Bora prevails in the areas around Ajdov_??__??_cina in Slovenia and Trieste, Senj, and Karlobag at the Adriatic sea coast, where the local topographic situations are favorable as one of the causing factors. Distribution of Bora region is presented as shown in Fig. 9.
Finally, schematic cross-section was drawn along a line WSW-ENE passing Senj, where Bara is the strongest at the coast, as given in Fig. 10.
