Francesco Denza was born in Neaples in 1834. He was
a very precocious student (liceal degree at 14 years old) and interested
in scientifical subjects. He conciliated both scientific and religious
vocations entering at 16, after he had got the "certificate of engineer
of bridges and streets", the Barnabite Fathers' Order, famous for its wide
cultural interests.
During the three years of theological studies in
Rome, he met and frequented Angelo Sacchi, a father Jesuit, famous astronomer,
who introduced him to studies of astronomy and meteorology. Assigned as
maths teacher to Real Collegio of Moncalieri, where he stayed for 35 years,
he moved to Piedmont where, in 1857, he got a physical degree and the following
year he was ordined priest.
In 1859 he got the Real Collegio Observatory to
be built and at the same time he planned to create a meteorological network
spread in all Italy, working with a unique method and with the same kind
of instruments and being under an only management. After 25 years the Association
he had planned took the name of Italian Meteorological Society and published
monthly an important gazette which reported the tables of the daily observations
of Moncalieri (max. and min. temperature, winds, clouds, ozone) with news
of the other 2OO observatories connected with it and with informative notes
about a lot of natural phenomena.
As the project of the meteorological network was
being built up, Father Denza was called for to Rome to reorganize the Specola
Vaticana. He devoted the last years of his life to the ancient Roman observatory,
which was equipped for astronomy, meteorology, seismology and geomagnetism.
He died in Rome in 1894.
Father Denza can be defined more a scientific manager
than a scientist. If we glance through his wide bibliography, we will realize,
by the kind itself of his publications (notes, memorials, relations, divulgative
texts) and by the variety of the subjects he treated (atmospherical phenomena,
earthquakes, eclipses, sunspots, terrestrial magnetism, altimeter etc.),
that his work is not in the theoretical sphere of speculation but in the
practical sphere of observation, divulgation and organization, at local,
national and international level. In fact his scientific interest was about
a group of natural phenomena, meteorology, geography, physics, geomagnetism
and astronomy, which are connected to each other, so a wide and systematic
work of observation, collection and collation of data had to be planned.
He worked in this direction, using the method of
phenomenon's survey, projecting and improving instruments (anemograph and
recording rain gage) and organizing a modern teamwork with the help of
correspondents and collaborators from three continents.
The most important result of his work was his network,
that is a reading-system of meteorological-data from 254 observation places
around the world, up to Moncalieri's Observatory.
That was a great intuition. The data of a single
observatory give us quite a correct idea about the regional meteorological
situation. But we cannot go further because there are no mathematical formula
able to calculate temperature, pressure and humidity working at a distance.
We have also to consider that the weather of all countries is influenced
a lot by the topographic exposition (latitude, altitude, distance from
the sea and from big lakes, disposition of rilief and vegetation). So it
is important that the reaching of data is made around the world and everywhere
in the same way, so that a world weather scheme of a definite moment is
created: this is the starting point for a climatological research.
The Observatory founded in 1859 by
Father Francesco Denza is in the Real Collegio, an ancient institute of Moncalieri at 3O
of via real Collegio (latitude 44°59'52" N; longitude 7°41'43"
E Greenwich; altitude of the threshold 247,78 m. over the sea level).
The Observatory's instruments, that were in part
projected by Father Denza, are:
- barometer (it measures the atmospheric pressure);
- barograph (it records the atmospheric pressure);
- thermometer (it measures the air temperature);
- thermograph (it records the air temperature);
- psycometer (it measures the absolute and relative humidity);
- hygrograph (it records humidity);
- anemograph recording rain gage or "anemojetografo Denza" (it records the wind speed and the quantity of precipitation);
- sunshine recorder (it records sun hours);
- hygrothermograph (it records air temperature and humidity);
- nephoscope (it measures wind direction and wind altitude speed);
- altimeter (it measures altitude).
These instruments are in an instrument shelter installed
on the balcony balaustrade and exposed to NW 2O m. high from the ground
and at 267,5O m. over the sea level. The recording rain gage, instead,
is in an aluminium cab with funnel at 26 m. from the ground and 274 m.
over the sea level. Some of these instruments have a great historical importance
because they are the standard for barometers and thermometers for most
of Italian observatories.
In this observatory, data of temperature , air humidity,
wind speed, rain snow, atmospheric pressure, ozone presence, state of the
sky and phenomena were recorded daily, six times a day (at 6, 9, 12 a.m.,
3, 6, 9 p.m.).
From the second part of our century, only max. and
min. temperatures and precipitations were daily recorded; from the eighties,
data have been transferred on a data carrier. The Observatory is still
working.
Today meteorological monitoring, because of its detailed
series of information, is an essential instrument of work for people from
different working areas and with different aims: from the meteorological
service manager to the civil safety engineer, from the scientist to the
historian.
The research about climatic series of past data
, like those of Moncalieri's Observatory, makes for example an historian
able to find the correspondence between climatic phenomena and social-historical
facts (migrations, famines, epidemies), and a scientist able to study great
climatic changes or to reconstruct the natural distribution of ozone in
pre-industrial age.
Instead the analysis of recent climatic data series
has immediate and practical application. Examples may be the verification
of air pollution level (showing, for example, the quantity of ozone or
the water acidity level), the control of great natural catastrophes effects
(inundation, avalanche, cyclone), or the prevention against common atmospheric
phenomena (fog, winds, ice).
First of all the weather forecast is essential in
the field of prevention, where the previous notice of a natural calamity
(inundation, landslide, etc.) allows to put into action alarm systems for
the civil protection and for a good territory management.
The forewarning is also very helpful because most
of our working activities, from agriculture to tourism, from land transport
to air and sea navigation are deeply influenced by it. In fact it allows
farmers to organize their work according to the weather forecast or to
contrast damages caused by ice, over precipitation, or dry weather with
planned intervention; it also gives indication about altitude winds and
land winds strictly necessary for pilots and sailors.
The weather forecast is the probabilistic knowledge
of the evolution of meteorological phenomena (winds, precipitations etc.)
about a more or less wide country. It is made from meteorological monitoring
data and it can be a long-term forecast or a short-term forecast.
For a long-term forecast, for example about a season,
have to be confronted meteorological monitoring data about the latest decade,
because the weather repeats itself more or less in the same way.
For a short-term forecast (with an advance of max.
6 or 7 days) the numerical forecast method is used. The starting point
is given by numerous observations about the contemporaneous temperatures
of two contiguous air masses at different altitudes, the pressure variation
and the speed of this variation and, for the knowledge of wind situation,
the more or less closeness of isobars.
These data, which are useful for the study of the
development of cyclones and anticyclones, responsable of meteorological
phenomena changes, are mathematically elaborated with the physic laws of
thermodynamics and mechanics of fluids that air, being a fluid, respects.
