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Review paper
UDC 551.5
Andrija Mohorovi~i} as a meteorologist
Mirko Orli}
Department of Geophysics, Faculty of Science, University of Zagreb, Zagreb, Croatia
Received 19 November 2007, in final form 10 December 2007
Andrija Mohorovi~i}’s meteorology-related activities are reviewed. It is
shown that he was involved in teaching and professional work in meteorology
throughout his professional career, and in meteorological research until his
early forties – i.e. before switching to seismological research and arriving at
the famous discovery of discontinuity between the Earth’s crust and its mantle.
Mohorovi~i} taught meteorology at the Nautical School in Bakar (1882–1891)
and later at the University of Zagreb (since 1894). As for the professional
engagement in meteorology, his major achievements were foundation of me-
teorological station in Bakar (1887), start of meteorological forecasting in
Croatia (1893), and establishment of the network of Croatian meteorological
stations (1901). Mohorovi~i}’s meteorological research included, but was not
limited to, the climatological investigation of clouds and their movements in
the Bakar area, the study of tornado that struck Novska, and an early study
of the Zagreb climate conditions. As demonstrated in a recent publication,
Mohorovi~i} also made pioneering contribution to the investigation of atmo-
spheric rotors, by describing in some detail a vortex with horizontal axis he
had observed from Bakar (1889); this discovery influenced later research of
similar phenomena in England and Germany, but was forgotten by the inter-
national scientific community some fifty years later.
Keywords: Andrija Mohorovi~i}, teaching of meteorology, Croatian meteorolo-
gical network, atmospheric rotors.
1. Introduction
Andrija Mohorovi~i} spent most of his professional life working at two
institutions: from 1882 to 1891 at the Nautical School in Bakar and from 1891
until his retirement in 1921 at the Meteorological Observatory (which later
changed the name to the Institute of Meteorology and Geodynamics and final-
ly to the Geophysical Institute) in Zagreb (Skoko and Mokrovi}, 1982). Both in
Bakar and in Zagreb he was engaged in teaching, research and professional
activities in the field of meteorology, although under different conditions, with
various collaborators and with different outcomes. It therefore makes sense to
consider his activities in the two cities separately. Altogether, Mohorovi~i}
GEOFIZIKA VOL. 24 No. 2 2007
published about twenty papers related to meteorology (Orli}, 1998a). The
present review is based on a subset of these papers, selected so as to cover the
most important results of his work.
2. Bakar years
Andrija Mohorovi~i} came to Bakar at the age of twenty-five, after com-
pleting the study of physics and mathematics and passing the teacher exam at
the University of Prague and after working for a while at high schools in
Zagreb and Osijek (Skoko and Mokrovi}, 1982). At the Nautical School in
Bakar he taught mathematics, physics and meteorology, the latter being of
particular importance in the nautical school curricula because of its signifi-
cance for the future seamen. It is interesting that during his study in Prague
Mohorovi~i} did not attend meteorological courses (Orli}, 1998b), and it would
thus appear that teaching in Bakar encouraged him to master this scientific
discipline as an autodidact. It is not exactly known which books he used in the
process, but in his papers from the period he cited works by A. Sprung (Lehr-
buch der Meteorologie, Hamburg, 1885) and W. Ferrel (Recent Advances in Me-
teorology, Washington, 1886), implying that he did not restrict himself to Ger-
man sources which would be the first choice to somebody whose university
study was mostly conducted in German.
At the Nautical School in Bakar Mohorovi~i} established a meteorological
station, which became operational on 1 May 1887. Already before that he carried
out some meteorological measurements, but serious activities could start only
when, with the help of the government, he acquired a set of basic instruments
(a barometer, a psychrometer, maximum and minimum thermometers, an
ombrometer and a heliograph). In his own words, the meteorological station
was established »firstly, as a support for the lectures; secondly, because these
lectures are of big importance for students which will become seamen; thirdly,
because of the very special orographic position of Bakar« (Mohorovi~i}, 1888).
From this citation it may be concluded that from the very beginning he in-
tended to use the station to support the lecturing but also to do some research.
At the time it was usual for high school teachers to get involved in other
activities besides the teaching. High schools used to publish annual reports to
which the employees were expected to contribute scientific and professional
papers, and the schools enabled teachers active in research and publishing in
different areas to interact on a regular basis. For instance, Mohorovi~i}’s
colleagues in Bakar were Narcis Damin, a well-known researcher of spiders,
Juraj Cari}, author of nautical textbooks and writer on the life of seamen, and
Aleksandar Lochmer, author of the English language textbook, grammar and
dictionary (Marochino, 1982). Among the colleagues from the Nautical School
it is worth to mention also Anton M. Zuvi~i}, teacher of nautical courses and
an experienced sea captain, who enthusiastically helped Mohorovi~i} to per-
76 M. ORLI]: ANDRIJA MOHOROVI^I] AS A METEOROLOGIST
form observations at the newly established meteorological station. In his texts
Mohorovi~i} often compares meteorological conditions in Bakar with those in
Rijeka. The meteorological station at the Nautical Academy in Rijeka was led
since 1877 by Peter Salcher, professor of physics and mechanics. It is interest-
ing that Salcher collaborated with Ernst Mach in a pioneering study of air flow
around bullets. Mach, the famous physicist and Mohorovi~i}’s professor at the
University in Prague, visited Salcher in Rijeka in spring 1887 (Smokvina,
2004). It is not known if Mach and Mohorovi~i} met on that occasion, but it is
obvious that in Rijeka Mohorovi~i} could get additional stimulus for his re-
search activities.
How seriously Mohorovi~i} approached the meteorology can be seen from
the fact that he was not contented with the routine equipment of the meteoro-
logical station, but decided to add to the basic instruments a device he had
constructed – a nephoscope – which enabled determination of the direction
and speed of the motion of clouds (Figure 1). Such instruments were used at
the time to infer the motion in the higher layers of the atmosphere, and thus
to supplement the rare data collected by researchers during balloon flights.
For his version of the nephoscope Mohorovi~i} made use of the school-owned
GEOFIZIKA, VOL. 24, NO. 2, 2007, 75–91 77
Figure 1. Nephoscope as constructed by Mohorovi~i} (1888).
camera obscura. His technical solutions ensured high precision, keeping at the
same time the construction costs low. In order to use the collected data as
thoroughly as possible, Mohorovi~i} derived trigonometric expressions that
enabled him to determine not only the horizontal but also the vertical compo-
nent of velocity of the cloud movement (Mohorovi~i}, 1889a). He conducted
the measurements very carefully, and so, for example, he states that cloudi-
ness »determines Mr. Zuvi~i} with me simultaneously, so that we check each
other, and we finally note the average value of the two estimations in the diary«
(Mohorovi~i}, 1891). He also paid considerable attention to the measurement
errors and the necessity to take them into account during the analysis.
Most of the results of observations and measurements performed at Bakar
Mohorovi~i} presented in three papers (Mohorovi~i}, 1889a, 1891, 1892) that
enabled him to earn the doctoral degree at the University of Zagreb in 1893.
The papers focused on climatological analysis of cloudiness, cloud types and
related air flow, with the results being presented in numerous tables. Thus,
for example, Mohorovi~i} discovers that there are two maxima of cloudiness in
summer, a larger one in the afternoon and a smaller one in the morning, and
only one maximum in winter, in the forenoon. He also notices that there is a
tendency for clouds to regularly align twice a day, at about 8 a.m. and 5 p.m.
The latter observation would nowadays be related to wave phenomena in the
atmosphere, and the changes in wave regime during a day to the changes of
atmospheric stability. Mohorovi~i} also finds that the surface winds turn with
the Sun in the forenoon and against the Sun in the afternoon, and that the
high altitude winds turn in the opposite direction. Regarding the wind speed
he emphasizes that there is the surface maximum close to the noon and that
the speed is lower in the morning and in the evening, with the high altitude
wind having the opposite diurnal variation. Such findings could be related to
the coastal circulation and its modification caused by complex topographic
effects in the Bakar area as well as to the atmospheric stability being much
higher overnight than during the day.
Despite the fact that Mohorovi~i}’s work focused on the climatological ana-
lysis of the data collected in Bakar, he did not overlook particular situations
that ultimately define the climate conditions. Description of one such situa-
tion is the subject of the paper that Mohorivi~i} published in the Viennese
journal Meteorologische Zeitschrift and that represents his most important
contribution to meteorology (Mohorovi~i}, 1889b). The paper deals with the
description of clouds and related air flow based on measurements and observa-
tions carried out on 18 October 1888 in the Bakar area. He summarized his
findings in a schematic presentation of the state of the atmosphere in a ver-
tical section extending from mountains over Bakar to Rijeka Bay (Figure 2).
During a bora event Mohorovi~i} observed a stationary cumulus cloud linger-
ing almost throughout the day over Kostrena, fragments of cumulus clouds
descending down the mountain slope, and stratocumulus clouds moving down-
wind in the higher altitudes. Based on these observations, as well as on addi-
78 M. ORLI]: ANDRIJA MOHOROVI^I] AS A METEOROLOGIST
tional observations and measurements performed at the ground and at the sea
surface, he concluded that the air flowed down the mountain slope, upwelled
over Bakar, moved in higher altitudes towards Rijeka Bay, where it down-
welled and flowed back to Bakar. This allowed Mohorovi~i} to conclude that a
vortex with a horizontal axis developed around the stationary cumulus cloud,
and that consequently the surface wind above Rijeka Bay had the direction
opposite to the bora. This description of the phenomenon was of great interest
to the journal editor J. Hann, who appended it with his commentary on
similar phenomena in South Africa, Greenland and England.
A recent historical study has shown that a phenomenon known today as
atmospheric rotor was for the first time described in detail in the above paper,
that Mohorovi~i}’s discovery influenced later research of similar phenomena
in England and Germany, but also that this contribution to the international
research of atmospheric rotors was forgotten some fifty years later (Grubi{i}
and Orli}, 2007). It is interesting to consider how the idea on the air flow over
mountains evolved in the works of Mohorovi~i}’s precursors and contempora-
ries (Figure 3). J. F. W. Herschel, son of the famous astronomer W. Herschel,
described in 1862 the air flow over a mountain in South Africa as well as the
wavelike flow in its lee (Herschel, 1862). W. Marriott, British researcher, sche-
matized in his 1886 paper the air flow over a mountain in England in a similar
GEOFIZIKA, VOL. 24, NO. 2, 2007, 75–91 79
Figure 2. Clouds and air flow observed by Mohorovi~i} on 18 October 1888, shown in the vertical
section extending from mountains (right) over Bakar to Rijeka Bay (left) (Mohorovi~i}, 1889b).
way (Marriott, 1886). However, three years later he changed this presentation
by introducing in it the atmospheric rotor as well as the counterflow at the
surface (Marriott, 1889). Most probably, Mohorovi~i}’s paper motivated this
80 M. ORLI]: ANDRIJA MOHOROVI^I] AS A METEOROLOGIST
Figure 3. Air flow over a mountain as schematized by Herschel (1862) (a), schematic presenta-
tion published by Marriott (1886) (b), and modified version of the latter (Marriott, 1889) (c). The
last presentation was published after its author got acquainted with Mohorovi~i}’s results ob-
tained for the Bakar area.
improvement: Marriott not only mentions Mohorovi~i}’s paper in his later
publication, but also includes in it the translation of the whole Mohorovi~i}’s
paper into English.
Mohorovi~i}’s German paper of 1889 was later cited in some of the best
meteorological textbooks of the time: it was thus mentioned by J. Hann (1901),
the respectable meteorologist and editor of the journal in which the paper had
been published, as well as by A. Wegener (1911), geophysicist who started his
career as a meteorologist but become famous for the continental drift theory
from which the plate tectonics theory later evolved. Finally, J. Kuettner (1938,
1939) mentioned Mohorovi~i}’s paper and related diagram several times in his
seminal papers, in which he dealt with the atmospheric rotors in the lee of a
German mountain. Thereafter Mohorovi~i}’s paper was not cited abroad any
more, and it seems that even Croatian scientists lost sight of his diagram.
Kuettner’s papers have motivated further measurements all around the world
as well as theoretical research of atmospheric rotors, which last to date. The
most recent large experiment dedicated to atmospheric rotors, called T-REX
(Terrain-Induced Rotor Experiment), was carried out in 2006 in the Sierra
Nevada area in the USA (Grubi{i} et al., 2004). The leader of the experiment
GEOFIZIKA, VOL. 24, NO. 2, 2007, 75–91 81
Figure 4. Andrija Mohorovi~i} (right) in company with Ivan Sto`ir (left), his predecessor at the
Meteorological Observatory in Zagreb. In the middle is Spas Vatsov, founder of the Bulgarian
Meteorological Service, formerly Sto`ir’s student at the High School in Zagreb.
was Vanda Grubi{i}, who graduated in geophysics from the University of
Zagreb and later earned a doctoral degree from the Yale University. To a large
extent her activities enabled the contemporary meteorologists to get familiar
with Mohorovi~i}’s pioneering contribution to the atmospheric rotor research.
3. Zagreb years
At the end of 1891 Andrija Mohorovi~i} started to work at the High School
(Velika realka) in Zagreb, and soon became the head of the Meteorological Ob-
servatory that operated in the framework of the school. Later, the observatory
broadened its field of work, changed its name several times and became an
independent institution (Skoko and Mokrovi}, 1982). Mohorovi~i} took over
the management of the observatory from Ivan Sto`ir (Figure 4), who was
professor of physics and who established the observatory on 1 December 1861.
Mohorovi~i} continued to maintain the observatory at the high professional
level, gradually substituted some old instruments by new ones (barograph –
Figure 5, thermograph, anemograph) and acquired several new instruments
(hygrograph, ombrograph, heliograph). From the text he wrote about equip-
ment of the observatory it is evident that he took great care of the instrument
positioning and calibration and of the correction of data collected (Moho-
rovi~i}, 1902).
From the very beginning of his work at the observatory Moohorovi~i} con-
sidered it as the central institution that should act as the focal point for all
other Croatian meteorological stations. Already in 1893 he established a net-
work of storm-observing stations, and in 1901 he managed to put 78 meteoro-
logical stations under the administration of the Zagreb observatory (Mohoro-
vi~i}, 1902). Before that, these stations were managed by the Royal Hungarian
Meteorological Agency in Budapest, Royal Croatian-Slavonian-Dalmatian Go-
vernment in Zagreb, Meteorological Observatory in Zagreb and various private
persons. With the governmental agreement and its financial support Mohoro-
vi~i} succeeded to gather all these stations in a single network and to partially
equip them with new instruments. In September and October 1901 he perso-
nally visited most of the stations in order to inspect the instrument positions,
to control whether they are operational and calibrated and to check the way
the observations are made. Because of the increased amount of work Mohoro-
vi~i} always tried to employ more people at the observatory, but it seems that
at best he had only one assistant, two clerks and a secretary (Penzar et al.,
1986). Assistants changed often, with Stjepan [kreb, Andro Gili} and Milan
Kova~evi} having lasting influences on Croatian meteorology.
Mohorovi~i}’s professional activity in Zagreb was not limited to the super-
vision of the Meteorological Observatory and the organization of the network
of meteorological stations. Already in 1893, after being repeatedly urged by
the editor of the Zagreb newspaper Agramer Zeitung, he started to publish
82 M. ORLI]: ANDRIJA MOHOROVI^I] AS A METEOROLOGIST
tentative weather forecasts (Mohorovi~i}, 1897b). At the end of 1894 he was so
disappointed with the results that he wanted to cease this activity. Being,
however, unable to resist further persuasion, he continued to publish the
forecasts. In the year 1896 he published 286 forecasts, out of which, according
to his analysis, 77% were successful. In his text on weather forecasting Moho-
rovi~i} mentions that the main goal of this activity is to gain knowledge, which
GEOFIZIKA, VOL. 24, NO. 2, 2007, 75–91 83
Figure 5. Barograph Sprung-Fuess, installed by Mohorovi~i} at the Meteorological Observatory
in Zagreb in 1903. Among other phenomena, this instrument recorded the passage of atmospheric
gravity waves caused by the fall of Siberian meteor in 1908.
will enable more successful forecasting in the future. From the available texts
it is difficult to understand how he actually made the forecasts. A glimpse is
provided by the statement that »there are two kinds of laws which govern the
weather; some are valid for the whole Earth or at least for a continent; the
others are specific to a country or even to a region in a country... The weather
forecasting thus rests on a proper understanding of general meteorological
laws as well as on a familiarity with climatological conditions prevailing in the
region for which the forecast is prepared« (Mohorovi~i}, 1897b). It seems that
initially Mohorovi~i} based the forecasts on the Zagreb data only, but that
later he succeeded in organizing the telegraphic data collection from a broader
area (Lisac, 1998). The forecasts were short; for example, on 26 July 1904
Narodne novine published the following announcement: »Partly cloudy with
thunders« (Lisac, 1998). After the World War I started, Mohorovi~i} ceased to
publish the forecasts: because of conscription he was left without assistants,
and due to difficulties in communication he lacked adequate information on
weather conditions in Europe.
Another professional activity that Mohorovi~i} had to accept was related
to the hail defense. At the beginning of 1901 he led a testing of five cannon
types »with the goal of seeing which system is the safest and the most simple,
and which system provides the largest effect under the lowest costs and the
minimum use of gunpowder« (Mohorovi~i}, 1901b). Thorough as usual he
involved two co-workers – captain \. ^a~kovi} and assistant S. [kreb – to
measure simultaneously with him the durations of reverberations after the
shots, so as to obtain the times as reliable as possible.
Despite the abundance of professional work he had to handle after his ar-
rival to Zagreb, Mohorovi~i} did not lose sight of other activities. As already
mentioned, in 1893 he earned the doctoral degree at the University of Zagreb,
and a year later he habilitated at the same university with a paper on tornado
at Novska (Mohorovi~i}, 1893). During the next twenty years he worked as an
adjunct lecturer, and later as an adjunct associate professor, offering courses
on different meteorological subjects (Introduction to general climatology, Spe-
cial climatology, Meteorology and climatology, On meteorological instruments
and their use, Practical instructions in observation at meteorological stations,
etc.). Later he supplemented these with some seismological courses (Ano-
nimus, 1894–1917). It should be pointed out that his laudatory review of M.
Milankovi}’s book Théorie mathématique des phénomènes thermiques produits
par la radiation solaire contributed to its acceptance by the Academy of
Sciences and Arts in Zagreb and a Parisian publisher and to its publication in
1920 (Makjani}, 1979). In the book the famous astronomical theory of climate
changes was thoroughly developed for the first time.
The first Mohorovi~i}’s research activity after his arrival to Zagreb was
motivated by tornado that struck Novska on 31 May 1892 and whose effects he
analyzed as the governmental appointee. After surveying Novska and its sur-
roundings Mohorovi~i} compiled a detailed report, in which he skillfully com-
84 M. ORLI]: ANDRIJA MOHOROVI^I] AS A METEOROLOGIST
bined pieces of information from different sources to create a comprehensive
idea of the phenomenon (Mohorovi~i}, 1893). For example, he noticed that the
train coaches at the local station were expelled from the railway in different
directions (Figure 6), which led him to conclude that the flow in the tornado
was cyclonic, i.e., counterclockwise. From the information that a coach weight-
ing 13 t was thrown 30 m away he calculated that both the horizontal and the
vertical components of the near-ground wind speed amounted to about 70 m/s.
From the directions in which the trees were scattered in a nearby forest he
concluded that two tornados, with diameters equaling 800–1200 m and 2300 m,
passed over the forest, and that distance between their paths was 1200–1500 m.
He also constructed a synoptic map (Figure 7) and noticed four weak de-
pressions as well as a large temperature gradient in Croatia and neighboring
countries. On the basis of recorded times at which the employees of Croatian
telegraph stations switched off electricity because of thunder, he demonstrat-
ed that the front moved from the southwest to the northeast with a velocity of
20–30 km/h. Finally, he completed the report with the testimonies on a strong
hail, on the shape of vortices as well as on a very low pressure in their centers
– the last provided by a woman who claimed that during the passage of the
tornado »she could not, together with a servant, open a room door, and after
the tornado moved on the door opened by itself, and the windows fell into the
room together with frames« (Mohorovi~i}, 1893). He did not attempt the
GEOFIZIKA, VOL. 24, NO. 2, 2007, 75–91 85
Figure 6. Position of the train coaches expelled from the railway by tornado that struck Novska
on 31 May 1892, according to Mohorovi~i} (1893).
dynamical explanation of the phenomenon, but only remarked that its cause
has to be sought in the large temperature gradient in Croatia.
Upon taking over the management of the Meteorological Observatory in
Zagreb, Mohorovi~i} inherited from his predecessor meteorological time series
whose length exceeded 30 years. This enabled the first analysis of climate
conditions in Zagreb to be attempted. As the parameter most appropriate for
the start of investigation Mohorovi~i} chose precipitation (Mohorovi~i}, 1897a).
After a typically conscientious discussion of conditions under which the mea-
surements were performed as well as of the data quality, he applied harmonic
analysis on the precipitation time series and found a 30.5 year periodicity. By
applying the same method on the fluxes of the Sava River measured at Stara
Gradi{ka he found an oscillation of the same period, with the river flux maxi-
mum lagging two years behind the precipitation maximum. Thus he made an
86 M. ORLI]: ANDRIJA MOHOROVI^I] AS A METEOROLOGIST
Figure 7. Synoptic map that Mohorovi~i} drew for 14 h on 31 May 1892 (Mohorovi~i}, 1893). This
is the first such map published in Croatia.
early contribution to hydrology. In the remainder of the paper he determined
some additional smaller periods, and then proceeded to investigate the mean
annual course and to determine the precipitation maxima in June and October,
a maximum of the number of days with precipitation in June and a maximum
of the precipitation intensity in October. He concluded the paper by announc-
ing a similar analysis for other meteorological parameters, which, however,
did not materialize.
In his last scientific paper dealing with meteorology Mohorovi~i} consider-
ed vertical profile of temperature (Mohorovi~i}, 1901a). In the study he used
the temperature data simultaneously measured at Zagreb and on the mountain
of Sljeme as well as the data the foreign researchers collected during balloon
flights and using some new instruments – especially probes equipped with
autographs. After discussing the data taken up to a 12 km height Mohorovi~i}
hypothesizes that »the temperature at a 20 km height is 110–120° lower than
at the surface of the Earth and that at a 30 km height it is 150–160° lower.
From this we can conclude that the temperature at the upper limit of the
atmosphere is very close to the absolute zero« (Mohorovi~i}, 1901a). Shortly
after this paper was published the stratosphere was discovered, which disprov-
ed Mohorovi~i}’s assumption on the constant decrease of the temperature
with height.
4. A big career turn
Around 1900, in his early forties, Andrija Mohorovi~i} quitted meteoro-
logical research and turned to another field – seismology. So, at the moment
when a decade of his efforts aimed at improving the Meteorological Observa-
tory in Zagreb and establishing the network of meteorological stations cul-
minated, he decided to proceed with the professional and teaching activities in
meteorology but also to refrain from using the data collected at the network in
his further research. Instead, he devoted himself to the organization of seismo-
logical station and to the study of seismology, for which he needed another
decade because obviously the governmental support for seismology was not
better than for meteorology. After that, he started research in seismology,
which soon resulted in discovery of the discontinuity that separates the Earth’s
crust from its mantle (Skoko and Mokrovi}, 1982; Herak and Herak, 2007).
This is Mohorovi~i}’s most important scientific achievement, accomplished in
his early fifties after a risky turn in the scientific career. What motivated him
to such a move?
As far as is known, Mohorovi~i} did not left behind any memoirs or letters
that could explain this decision. However, careful studies of his published pa-
pers provide some clues on the possible motivation. Thus, for example, when
writing on the climate of Zagreb he emphasizes that for the research of
climate changes »we should have at disposal about 1000 years of observations.
GEOFIZIKA, VOL. 24, NO. 2, 2007, 75–91 87
Since we do not have for any of the meteorological parameters the time series
that is longer than 100 years, we ought to relegate the secular periodicity
problem to our far descendants« (Mohorovi~i}, 1897a). From this it may be
concluded that he did not consider the available meteorological data, even
those originating from the oldest stations, suitable for the climate change
research. Regarding the short term processes, he presumably missed the data
documenting conditions in the higher layers of the atmosphere, especially
because at the very beginning of his scientific career he dealt with meteo-
rological problems in all the spatial dimensions. The wrong conclusion on the
vertical temperature profile (Mohorovi~i}, 1901a) had to draw his attention to
the importance of new instruments that were revolutionizing research of the
free atmosphere at the time, but it is not clear whether he did not manage to
equip his meteorological network with such instruments because of a lack of
financial support or due to the small number of co-workers.
Apart from the lack of high-quality data, there are some other reasons
that may have estranged Mohorovi~i} from meteorology. We know that he was
unsatisfied with the weather forecasts he was forced to publish (Mohorovi~i},
1897b). At the beginning of the 20th century the sense of frustration was
widespread among the meteorological forecasters (Friedman, 1989), due to the
impossibility of producing successful forecasts on the basis of physically found-
ed methods and the consequent need to resort to statistical methods. The fact
that Mohorovi~i} himself was aware of shortcomings of the theoretical ap-
proach to meteorology is evident from a text in which he states that the even-
tual task of the meteorologist is »to formulate differential equations describ-
ing motion of the air, and to obtain as an integral the general circulation of the
atmosphere and as particular integrals the cyclones, anticyclones, tornados
and thunderstorms. We are still far from completing this task …« (Mohoro-
vi~i}, 1901a). During the second half of the 19th century a lot of effort went
into application of both the hydrodynamic and the thermodynamic laws to the
atmosphere. The problem, however, was that these two lines of research were
separated (Friedman, 1989). For the first time it was V. Bjerknes and his
collaborators who started to relate the atmospheric circulation to the changes
of density and the latter to the variability of temperature and humidity. This
ultimately led to a new approach to the weather forecasting, but at that time
Mohorovi~i} was already retired.
After switching from meteorology to seismology Mohorovi~i} succeeded to
organize measurements that were at the time comparable with the best in the
world, whereas in his research he could for the first time combine empirical
and theoretical approaches: it was exactly such a methodology that enabled his
discovery of the discontinuity between the Earth’s crust and the mantle. This
discovery had a direct impact on the development of geosciences and it ele-
vated Andrija Mohorovi~i} to one of the greatest geoscientists of all times. As
already mentioned, his discovery of the atmospheric rotors was also respected
by the international scientific community. However, the investigation of such
88 M. ORLI]: ANDRIJA MOHOROVI^I] AS A METEOROLOGIST
meteorological phenomena was slow in developing, and Mohorovi~i}’s con-
tribution – although incorporated in the findings of his successors – was
gradually forgotten. Still, already with this work he showed an ability to
collect high-quality data and to arrive at an important result after carefully
analyzing the data. Some recent numerical simulations have shown that dur-
ing a bora event the atmospheric rotors may develop (Gohm and Mayr, 2005),
thus verifying the discovery Mohorovi~i} achieved almost 120 years ago and
fulfilling his dream about the unity of empirical and theoretical research in
this branch of meteorology. The fact that it took so much time for the unifica-
tion to occur, during which geophysical fluid dynamics evolved on one hand and
electronic computers and numerical methods developed on the other, shows
that the scientific progress depends on many factors and that a successful
scientist must be able to recognize when a problem is ripe for solution.
Acknowledgement –The present review of the meteorological activity of Andrija Mohoro-
vi~i} was prepared as a contribution to the events marking the 150th anniversary of his birth.
I am indebted to Dr. Vanda Grubi{i} for contributing to the analysis of Mohorovi~i}’s early
involvement in the atmospheric rotor research. The work was supported by the Ministry of
Science, Education and Sports of the Republic of Croatia (grant no. 119–1193086–3085).
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SA@ETAK
Andrija Mohorovi~i} kao meteorolog
Mirko Orli}
U ~lanku se iznosi pregled aktivnosti Andrije Mohorovi~i}a u podru~ju meteoro-
logije. Pokazuje se da je kao meteorolog bio uklju~en u nastavni i stru~ni rad tijekom
cijelog svojeg profesionalnog djelovanja, te da se znanstveno bavio meteorologijom do
svojih ranih ~etrdesetih godina – dakle, prije nego se posvetio znanstvenom seizmo-
lo{kom istra`ivanju i tako do{ao do ~uvenog otkri}a plohe doskontinuiteta izme|u
Zemljine kore i pla{ta. Mohorovi~i} je predavao meteorologiju na Nauti~koj {koli u
Bakru (1882–1891) te kasnije na Sveu~ili{tu u Zagrebu (od 1894. godine). [to se ti~e
stru~nog rada u podru~ju meteorologije, najzna~ajnija su mu postignu}a utemeljenje
meteorolo{ke postaje u Bakru (1887), po~etak meteorolo{kog prognoziranja u Hrvatskoj
(1893) i uspostavljanje mre`e hrvatskih meteorolo{kih postaja (1901). Mohorovi~i}eva
meteorolo{ka istra`ivanja uklju~ivala su, izme|u ostalog, klimatolo{ku studiju oblaka i
90 M. ORLI]: ANDRIJA MOHOROVI^I] AS A METEOROLOGIST
njihovog gibanja u podru~ju Bakra, izu~avanje tornada koji je pogodio Novsku te rano
istra`ivanje zagreba~kih klimatskih prilika. Kako je pokazano u jednom nedavno objav-
ljenom ~lanku, Mohorovi~i} je tako|er dao pionirski doprinos istra`ivanju atmosferskih
rotora, detaljno opisuju}i vrtlog s horizontalnom osi {to ga je opa`ao iz Bakra (1889); to
je otkri}e utjecalo na kasnije istra`ivanje sli~nih pojava u Engleskoj i Njema~koj, ali ga
je nakon pedesetak godina me|unarodna znanstvena zajednica zaboravila.
Klju~ne rije~i: Andrija Mohorovi~i}, nastava meteorologije, hrvatska meteorolo{ka mre-
`a, atmosferski rotori.
Author’s address: M. Orli}, Department of Geophysics, Faculty of Science, University of Zagreb, 10000 Zagreb,
Horvatovac bb, Croatia, e-mail: orlic@irb.hr.
GEOFIZIKA, VOL. 24, NO. 2, 2007, 75–91 91
