Gregor Johann Mendel Meteorologist

Even though Johan Gregor Mendel achieved the greatest fame in genetics, his merits in the field of meteorology cannot be overlooked either. He did not only measure the air temperature, but also the amount of precipitation, air pressure, and the amount of ozone, he also carried out phenological observations, observed the number of sunspots and measured the height of the groundwater level in the grounds of the monastery on Mendel Square. He also described the occurrence of a tornado in the vicinity of Brno.

5 Dec 2022 Jarmila Burianová Kevin Francis Roche

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Mendel and meteorological measurements in Brno

Even though Johan Gregor Mendel posthumously achieved his greatest fame in genetics, his merits in the field of meteorology should also not be overlooked. In the 1840s, Dr. Pavel Olexík was performing meteorological measurements at St. Ann’s general hospital in Brno. From at least 1857, Mendel was making concurrent measurements and observations at the nearby monastery and representing Dr. Olexík in his absence, and officially continued his measurements after his death. He wrote everything down very carefully, adding detailed notes, and later published the results of their combined measurements in the press of the time (Fig. 1), and sent the records of measurements and observations to the Central Methodological Institute in Vienna. He made his last entry six days before his death.

Figure 1. Mendel’s graphical and tabular overview of selected meteorological readings for Brno in 1862. These are compared to fifteen-year average values based on the meteorological measurements of Dr. Pavel Olexík.

He showed a great interest in meteorology, measuring not only air temperature but also levels of precipitation, air pressure and ozone levels. He also carried out phenological observations, counting the number of sunspots and measuring groundwater levels in the grounds of the monastery on Mendel Square, which was unique in his time. He also attempted weather forecasting using a scientific approach and made a point of condemning non-scientific approaches.

Studies on tornados and urban heat islands

In addition to his regular observations, he made a note of some extreme phenomena. Of great importance was his study of the tornado that passed over the Old Brno monastery on October 13, 1870, to which he was an eyewitness. He not only described the course of the entire event but also gave a physical explanation of the entire phenomenon, which was a rare occurrence of a clockwise wind vortex. His great interest in meteorology is also confirmed by the fact that, through his measurements, he discovered that the air temperature in the centre of the city was higher than that in the outskirts. Meteorologists only began to pay attention to the phenomenon ‘urban heat islands’ much later.

The Brno temperature and precipitation series

If we assess Mendel’s activities from the point of view of research activities at the current Department of Geography, then we have to appreciate his observational contribution to the compilation of the Brno temperature series (1799 to the present, the second longest temperature series in the Czech Republic after Klementinum in Prague) and precipitation series (1803 to the present − the longest line in the Czech Republic). These allow us to analyse the long-term variability of air temperatures and precipitation, expressing both the influence of natural climate-forming factors and the influence of the intensifying greenhouse effect due to human activity. He also made a significant contribution to the popularisation of meteorological measurements and their expansion in Moravia and Silesia. The tornado recorded by Mendel became part of the long-term chronology of tornadoes for the territory of the Czech Republic, starting as early as 1119.

Although meteorology and climatology have made enormous progress since Mendel’s time, his footprint and legacy remain in Moravian meteorology to this day.

Climatology at the Department of Geography

Current climatological research at the Department of Geography covers a wide range of issues. These relate to the long-term variability of the climate in the Czech lands and in Central Europe. In addition to modern meteorological measurements and observations, existing research is based on documentary sources (written records of weather and related phenomena in various types of documents) and analysis of tree rings (their width, density of late wood, analysis of the content of stable isotopes). These made it possible to reconstruct air temperature, precipitation and drought episodes over the last few centuries (see Fig. 2).

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Figure 2. Long-term fluctuations of annual precipitation totals in the Czech lands in the period 1501–2020 and average annual air temperatures in Central Europe in the period 1501–2020, reconstructed according to documentary sources (precipitation in green, temperatures in red) and instrument measurements (blue). Precipitation and temperature values are expressed in deviations from the average of the period 1961–1990. The dotted lines delineate the 95% confidence interval of the reconstructed values. While precipitation, in addition to great variability from year to year, has remained approximately at the same level during the last 520 years, air temperatures have clearly seen their dramatic rise since the end of the 19th century, attributed especially to the strengthening of the greenhouse effect since the second half of the 20th century.

Based on documentary sources, long chronologies of floods, storms, tornados and hailstorms were also compiled, which made it possible to study their frequency, intensity, seasonality and causes. Furthermore, the impact of these extremes on human society was studied in the form of an analysis of the damage caused or the loss of life. Knowledge of long-term climate variability and hydrometeorological extremes on the scale of the last few centuries thus covers a wide period with the predominant influence of natural climate-forming factors and with the gradually increasing influence of human society, which well describes the exceptional character of current climate change in the context of at least the last 500 years. At the same time, this enables us to better understand and evaluate the predicted climate changes and their impacts in the coming decades.


Brázdil, R., Valášek, H., Macková, J. (2005): Meteorologická pozorování v Brně v první polovině 19. Století [Meteorological observations in Brno in the first half of the 19th century]. Archiv města Brna, Brno. (in Czech)

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Brázdil, R., Dobrovolný, P., Mikšovský, J., Pišoft, P., Trnka, M., Možný, M., and Balek, J. (2021): Documentary-based climate reconstructions in the Czech Lands 1501–2020 CE and their European context. Clim. Past Discuss.

Translation: Kevin F. Roche
Editor: Zuzana Jayasundera

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