Rainfall acidity as related to the air mass trajectory: A study of the influence of time prior to precipitation

The influence of the regions crossed by the air mass before the precipitation in the rainwater acidity was analyzed. Logroño, a remote station in the North of Spain was chosen for the analyses. NOX and S-compounds emission, radiation at the top of the atmosphere and low cloudiness were taken to reproduce the ability of the region in the emission and transformation of the pollutants. Results prove that the regions crossed by the air masses from 48 hours until 24 hours before the precipitation, were more important than the regions run by the air masses from 24 hours before until precipitation to explain the rainwater pH.