"LIFE" said the American comedian C. Fields, "is just one darned thing after another" And so it is with our weather. If you were to ask a meteorologist what is meant by "weather", he or she might suggest that it comprises short term variations in such properties of the atmosphere as temperature, rainfall, humidity, cloudiness, wind and several others, described as they change from minute to minute, hour to hour, or even from one month to the next. At a more practical level, we experience the weather every day, and even without thinking about it very much, we know precisely what it is.
But the long term manifestations of the weather are considered to be part of "climate", and this is a much more woolly concept. Climate can be studied on a wide variety of different scales. The emphasis in recent years has been on the climate of the entire earth, but traditionally climatologists have tended to concern themselves more with the climate of regions or countries. And on an even smaller scale, studies have been made of the climate inside a single building, or of the variations in temperature and humidity over a single field of corn.
The father of modern climatology, Alexander von Humbolt, defined climate in 1845 as "all changes in the atmosphere affecting the human organs". Later climatologists, sensing perhaps that there was something unsatisfactory, indeed even humanly chauvinistic from the point of view of plants and animals, about this definition, came to think of climate as "the average of the weather" a description often still in use.
Meteorologists nowadays, however, feel that this is misleading because it implies that deviations from the average condition are in some way abnormal, ignoring the fact that in many cases, the unique and characteristic feature of a particular climate may be the way it deviates sharply and habitually from average values. Moreover, simple averages of some weather elements are quite meaningless one cannot sensibly speak of an average wind direction, for example, but the changing frequencies of northeast and southwest winds are of obvious importance.
Climatologists now feel that any concept of climate must embrace statistical concepts, such as the range and variability of the various climatic elements. So how do they define it now? The latest version is "The synthesis of weather events over the whole of a period statistically long enough to establish its statistical ensemble properties, largely independent of any instantaneous state". Simple, isn't it?