On May 4, 1700 the town of Salamanca made prayers to the Virgen de la Vega for rain. This fact, apparently just reached the category of historical anecdote may be part of a line almost unexplored climate research: the historical record. Miguel Angel Fuertes, scientist in the Department of Geology at the University of Salamanca, has followed this trail in the records of capiturales chapter of the Cathedral of Salamanca, a faithful witness of all types of incidents, including weather.
To do this, ideally you have data of temperature or atmospheric pressure taken with instruments, but are only reliable from the mid eighteenth century, so “if we try to study long-term changes in climate, we need information that goes beyond” explains the expert. In France and Switzerland have been studied during the grape harvest, as the maturation and growth of grapes depending on temperature and precipitation, so that is collected before or after. There are records dating back to medieval times on the dates that are beginning to harvest. So the first attempt Fuertes was Michelangelo contact designations of origin of Toro and Rueda, but your data will not be traced far back in time, especially in Toro, which suffered a fire file. A more fruitful idea was to search the records of the Cathedral Chapter of Salamanca, as did other scientists in Toledo and Barcelona. “The council was the governing body of the cathedral and met two or three times a week to treat any administrative matter concerning the diocese, so that in these books that survive from the late thirteenth century, include prayers , special prayers in times of drought or heavy rainfall, for rain to cease, “he explains. There were different types of prayers with the severity of the situation, from a simple sentence at the end of the Mass to go in procession or other special religious events in critical times. Prediction models “backwards” The data are interspersed between the everyday and the search is arduous, but exciting. “When it comes to prediction models that physicists use to model mathematically the behavior of the atmosphere, a number of parameters that fit the dynamic equations of the atmosphere,” he says. Currently, there is much detailed information as instrumentally, but “this model is to throw it to work backwards to see if it responds the same way in the past and it is important for any source of meteorological events. Although the documentary sources are not a precision tool, “give us an idea of extreme events”, but “we must analyze them carefully, they will be biased because not so worried about a drought in some seasons and in other for the agriculture. “ What he has done so far Miguel Angel Fuertes under the baton of Jose Abel Flores, an expert from the Department of Geology at the University of Salamanca, was just “tasting” to verify that the data exists. So, you can tell that the February 18, 1605 Philip III asked for prayers to end the drought, “which indicates a national problem” and that, conversely, the February 5, 1708 the prayers of Salamanca were for the rains to cease, because “the avenues of the river had caused a” lack of mills, “ie, they could not use the mills of the river, so called for” few steps were possible to avoid missing the bread “. Just three days later, on 8 February 1708, the record reflects that some owners of land located along the river come to the council to repair damage in the orchards. The abundance of this type of data required to invest much time to dive in the documentary sources if you want to do a rigorous scientific work thereon, as the researcher. Another source that investigators are considering are the tree rings (dendrochronology), since each year is reflected in one of these rings and their length depends on the humidity and temperature. No less curious are the log books, where he noted the wind direction, the form of clouds or precipitation. Also, speleothems, stalactites and stalagmites, are another source of information, because water is seeping into the caves, so that in times of more rain is deposited more limestone and stalactite grows each. Source: SINC DiCYT
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