VIEW OF THE SKY - 100TH ANNIVERSARY OF THE ZAGREB ASTRONOMICAL OBSERVATORY

The stamps have been issued in se-tenant, in a 10-stamp sheet (5 x 2) alternation, and the First Day Cover (FDC) was also issued. The definitions about meteorology written by Oton Kučera in his book “Weather - notes on meteorology” (“Vrijeme - Crtice iz meteorologije”) from the year 1897 are still topical. Meteorology is the science dealing with the weather, and its task is to find and investigate the mutual link of all the phenomena in the atmosphere and then give reasonable explanations of these phenomena. The majority of people nowadays equate meteorology with the weather forecast which leads to completely wrong conclusions. This is why the marking of such anniversaries from the history of meteorological observations and measurements in Croatia serves to enhance and expand the knowledge about meteorology in the wider social community. Records of unusual weather conditions on the area of present-day Croatia can be found since the 9th century. However, instrumental measurements have sporadically appeared not earlier than the 17th century, and they have specially intensified in the 19th century. It is accepted that the establishment of the meteorological observatory at the Croatian-Slavonian economic society in 18 Opatička Street also meant the beginning of measurements in Zagreb. They were started by Daniel Stanisavljević, financial adviser, on February 17, 1853. He received the instruments and other equipment from the meteorological administration in Vienna, and undertook observations three times a day following their instructions. He used to publish the data regularly in the newspapers, as well as in the weekly Economic Newspapers (“Gospodarske novine). In the course of a few years the station was moved several times, and in 1861 it was moved to Grič, into the newly founded Great Royal High School. The station was then headed by the physics teacher Ivan Stožir and he gradually developed the station into an independent observatory. This observatory was the institution that later developed into the Geophysical Institute “Andrija Mohorovičić”, the Meteorological and Hydrological Service of Croatia, Time Service and Seismological Survey of Croatia. Since then the Meteorological Observatory on Grič has been working permanently for 140 years, and their data are very precious and favourable for the research of the climatic changes in this part of Europe and one of the rare stations of this type with secular homogeneous series of data in the world. The high quality of the Zagreb data continued to be maintained by Stožir’s successors: academicians Andrija Mohorovičić, Stjepan Škreb, Josip Goldberg, Berislav Makjanić, Dragutin Skoko and their cooperators. On the foundations of the meteorological station they have developed the scientific field of geophysics, and then went on to develop its branches: meteorology, seismology, climatology, physical oceanography and related disciplines, as well as their application in various branches of human activities. Along with that they have developed geophysics to become an exact scientific discipline of world-wide reputation; they also developed the geophysical studies at the Geophysics department of the Natural Sciences Faculty of the Zagreb University, and raised it to international levels. In 1947, after detaching the meteorological service from the scientific-educational institution and by establishing the Administration of the Meteorological service, the present-day Meteorologic and Hydrologic Service of Croatia was established, and the net of meteorological stations in Croatia has started spreading rapidly. On October 1, 1953, regular weather observation started on the meteorological station on Zavižan, on the northern part of the Velebit mountain. The station is situated below the peak Vučjak, at 1594 m of above-sea altitude, which makes it the highest meteorological station in Croatia. At the beginning this station worked as a climatological station with three observations per day. Gradually the range of weather observations in this station was spread wider, and since September 1, 1964, regular daily reports are sent, catering for the needs of the prognostic services, which makes Zavižan a synoptic station, and they also provide systematic phenological observations (observations of developmental phases of forest trees and brushwood, as well as herbaceous plants). Measurements at the high-altitude station on Zavižan make it possible to determine the dependence of the changes of climatological elements on the above-sea-level height, which improves the comprehension of their spatial spread in the process of drawing cartographic presentations. The program of the meteorological station on Zavižan is much wider than the ones in the low-land stations. They perform special measurings of precipitation quantities origination from fog, then also measuring of the density of the snow cover and the content of water in the snow, determining the shape of the snow crystals and the vertical profile of measuring the minimal temperature of the air. The comparative microclimatological research in the individual pre-mountainous fittocenoses is very interesting and useful for the science and practice of forestry. Zavižan is a very important station for measuring the cross-border transmission of air pollution. From the meteorological station on Zavižan one has a wide view that makes it possible to observe many atmospheric phenomena even at great distances. Data derived about them have a useful application in warning about dangerous atmospheric processes. The position, program and quality of work of the meteorological station on Zavižan makes it a meteorological object of highest quality in Croatia. Professor Ivan Penzar, Dr.Sc. Milan Sijerković, Mr.Sc. Višnja Vučetić, Mr.Sc.