experience less precipitation (Basel: ). The driest regions of the country are, however, deep within the Alps (the inner valleys), particularly in Valais (Sion: ), which is often described as "semi-arid", but also in Graubünden (Chur: ). Precipitation levels do not always negatively correlate with sunshine hours. While Locarno is one of the wettest low-elevation locations in the country, it is also the one with the most sunshine hours (2,171). In comparison, the drier locations on the Plateau experience much less sunshine hours (Lucerne: 1,570, Zurich: 1,544). Being sheltered by the mountains, the regions well within the Alps also naturally experience more sunshine hours than the north side of the Alps (Sion: 2,093, Chur: 1,692). The widest range of climates in Switzerland is spread vertically. As the elevation above sea-level ranges from , many ecosystems are naturally found, from the regions of olives, vines, oaks and beeches, pines and firs, to those of the high mountain pastures, rhododendrons, and of eternal snow. In general, rainfall increase with elevation, while temperature decrease with it. Just above the plains and the foothills zone, at roughly , is the montane zone, which still encompasses numerous inhabited regions of the Alps and Jura Mountains. In the montane zone, which comprehends a large diversity of ecosystems, coniferous trees and snowfall progressively replace deciduous tree and rainfall. At roughly is the tree line, which marks the beginning of the Alpine zone. The latter marks the end of the inhabited regions as well, with a few exceptions, such as Juf. The final layer lies above . It is the snow zone (ice cap climate). It only concerns the high Alps, notably the Bernese Alps and Pennine Alps. The coldest meteorological station is at the Jungfraujoch, and overlook one of Europe's largest glaciers. The Jura and Alpine foothills have more precipitation than the plains, with an average of , while the high Alps may have over . Political divisions and greater regions As a federal state, Switzerland is composed of 26 cantons, which are further divided into districts and municipalities. Each canton was a fully sovereign state with its own borders, army and currency from the Treaty of Westphalia (1648) until the establishment of the Swiss federal state in 1848. There are considerable differences between the individual cantons, most particularly in terms of population and geographical area; hence seven larger and more homogeneous regions have been defined. They