ABSTRACT
By climate we mean the total experience of the weather at any place over some specific period of time. By international convention the period to which climate statistics relate is now normally thirty years, e.g. at the time of writing 1941-70, although we shall see arguments for preferring different periods for different purposes, particularly somewhat longer periods, such as fifty or a hundred years, and for preferring (as our grandfathers did) the decades that correspond to our linguistic usage based on our system of numbers, e.g. 1940-9…1970-9, and so on.
