Air temperature changes in Wrocław (SW Poland) in 1773–81 based on a newly discovered series of meteorological measurements

Abstract. The article presents a description of a newly discovered series of meteorological measurements made in Wrocław (SW Poland) in 1773–81 and its importance for climate analysis. The series is the third-oldest available for Wrocław. The 1773–81 observations were made by Johann Ephraim Scheibel on the premises of the Gymnasium that belonged to the Church of St Elizabeth (central Wrocław). Meteorological observations of air temperature and atmospheric pressure were made three times a day (morning, midday and evening) – or twice a day (morning and evening) for atmospheric precipitation, wind (including direction and force) and humidity. The meteorological registers were published in the newspaper Oekonomische Nachrichten der Patriotischen Gesellschaft in Schlesien issued in Wrocław in the years 1773–81. Between 1773 and 1776, the meteorological data were published in each weekly edition of the newspaper. From 1777 onwards, the data were published for the entire month and in three-month blocks in the last two years. In addition to the measurements, J. E. Scheibel also published, in the same source, between one and three pages of weather descriptions for each month or block of two to three months. The air temperature in Wrocław during the period 1773–81 was 1.2 °C and 0.3 °C warmer than in the respective equivalent periods 100 and 200 years later (i.e., 1873–81 and 1973–81) but 2.1 °C colder than in the most recent period (2013–21). The increase in temperature between the study period and the most recent period was greatest in summer (2.8 °C) and smallest in spring (1.4 °C).