Climate varies on all scales of time and space, bya large variety of reasons. However, before any discussion of reasons can be performed it is necessary to realize the very facts of climate variability by means of observations or reconstructions, respectively. In this book we focus on observed long-term trends of selected climate elements (temperature, precipitation, humidity, pressure ) as revealed by direct measurements of the Euro­ pean station network within the recent 100 years. Of course, there are a number of problems in detail: Reliability and accuracy of data, time series homogeneity, statistical confidence oftrends and so on. We hope that these problems are addressed in an instructive and, as far as possible, exhausting way. The main purpose of this work, however, was to provide a collection of trend charts which specify the regional particularities of observed climate trends in different months or seasons of the year leading us to an 'Atlas of observed climate trends in Europe'. Keeping in mind the recent World Meteorological Organization (WMO) climate nor­ mal (CLINO) period, we have also calculated the 1961-1990 trends.