Concise long-term forecasting is a thing of the future ! As, to some extent, the future of human experience can be planned and foreseen from the historical past, so should that of weather and climate, in the long-term sense, be predicted by the evidence provided from geological records.This revised edition of Dr. Brooks's book puts comprehensively and into an astonishingly short space most of what is a t present known of the geological record of climate, together with the latest theories concerning the evidence for historic climatic changes. Included, too, is the substance of most, if not all, the philosophies concerning the origin and causes of climatic change and of fluctuations of flood and drought, heat and cold.Among the many additions to the first edition of 1926 is the inclusion of Professor F. E. Zeuner's views on the timing and glacial history of the Qnaternary Ice Age. Zeuner adopts Milankovitch's theory of the changes in the obliquity of the ecliptic, that is the angle which the plane of the equator makes with the plane of the earth's orbit. The obliquity is regarded as having changed according to a mathematically calculated time-rhythm and Zeuner argues that this rhythm of obliquity corresponds to that of the ice advances and retreats in the Quaternary Ice Age. Dr. Brooks is at pains to stress that Zeuner realizes that this astronomical theory of how the oscillations were determind in no way explains this ice age aa a whole. The author does not neglect to discuss fully the earlier theory of changa in solar radiation which Sir George Simpson puts forward to explain these oscillations.Many of the factors which govern climatic changes through the ages are touched on and it seems probable that no single one by itself could possibly explain them. Short-and long-term changq may be due to different causes or a combination of two or three of them. Besides discussing causea and timing (he devotes an appendix to geological dating) of climatic changes and fluctuations, he gives a wealth of evidence, geological and palaeontological, geographical and oceanographical, and to this he adds an excellent summary of accumulated knowledge of climatic changes within historical times, that ie within the period commonly called the Post-Glacial. or Recent. These records are based on many written accounts of, for instance, great cold or floods aid other phenomena which are described or mentioned in literature ; but before the time of written annals, archaeology and tradition are largely relied upon as a source of information supported by cbngea in lake levels and the study of tree ringa and other physical phenomena.It is impossible to give even a brief review of thiR concentrated wealth of information upon a study which involves so much and so many sciences.This in itself is a testimony of the value of such a work to the student, he he meteorologically or geologically minded. It might be added that it is also R testimony to the writer's patience, memory and clear-headeclness-and, indeed to his life-long interest in the inter-...
The variations of temperature and rainfall in the British Isles during a period of two centuries or so have been studied on several occasions, but hitherto the subject of wind direction, equally im-Portant from the* meteorological standpoint, has been neglected. This compilation attempts t o remedy the omission. X fair amount of material is available, but the quality is very variable. Systematic weather diaries commence towards the end of the seventeenth century, giving one or more observations daily; at first there are serious gaps, but later the records become continuous. I t w a s found that the wind observations in many of the earlier weather diaries had never been tabulated ; the collection of the material has therefore been a decidedly laborious task. The presentation of the results also required thought. To give the actual frequencies of winds from eight points for all the years available would take a great deal of space; moreover, in that form the variations from year t o year are not readily grasped. Hence the various directions have been combined into " direction-frequency vectors, " which arc computed by assigning unit value to each observation of wind direction, irrespective of force. Although this practice does not give the actual resultant air-flow, for the earlier years it is the only practical method, and moreover it actually has certain advan. tages. The climatic character of all winds except the lightest depends more on their direction than on their force; for example, an east wind of 10 miles per hour differs more in its climatic character from a west wind of 10 miles per hour than the latter does from a west wind of 30 miles per hour, although the vector differences between them are the same. Secondly, the nuinerica! value of the vector, which we have termed the " constancy," gives a better idea of the steadiness of the wind from one direction than it would if account were taken o f velocity. The resultant directior.is literally the mean direction; this and the '' constancy " are analogous to mean temperature and the inverse of standard deviation, while direction frequencies are analogous to temperature frequencies. I t may be remarked that a similar method of computing resultant direction and " constancy " from daily observations of wind direction only has been in use for many years in t h e 8' Reseau Mondial."From the available material a choice was made of the three representative stations London, Edinburgh and Dublin, but one g a p in the London record was partly filled by series of observations from the " Downs " and one in the Edinburgh record by a series from Perth. Wherever possible, every change of series is covered by a n overlap, but no actual reduction from one series to another has been attempted in the main tables. T h e results are given for
BROOKS, I).SC., c'. 5 . L)lRST, B.A., and N. C.\KKCiTHIiRS, c . 5~ 1 . INTHOI~TCTION FCEE AIKFor the greater part of tho world, data of wind direction and velocity in the free air a r e very scanty or non-existent. In many countries pilot balloon observations have been taken for many years, but the wind roses obtained lrom these are inaccurate and misleading for two reasons: (a) because data are obtained only for days on which the balloon was not hidden by cloud ; and (b) because with increase of height fewer and fewer occasions of strong winds are included owing to the disappearance of the balloon in the dis ta m e . l l i t h radio methods of observation the first of these limitations is completely and the second partially overcome, but as yet the radio wind stations are too few, and have been in operation for too short a time, to describe the general circulation of the atniospherc at great hcights. To collect the necessary information will take many years, but it is thought that in the meantime a n extrapolation can t e effected by the use of thc data at present available. The object of the present paper is t c show that, given the resultant direction and velocity of the wind a t i i point in the free air and sonic measure of the scatter of the individual observations about the resultant, it is practicable to coastruct a wind rose to show the frequency distribution of winds of different directions and velocities which \\.auld be given by a long series of observations. The resultant tlirection and velocity, and the scatter, can be derived from a relatively short series of data with much greater accuracy than the frequencies of observations falling i n individual cells of direction and velocity, which generally give a rather irregular distribution, so that such a reconstruction is in effect a "smoothing" process. It is strictly analogous to the representation of the ideal distribution of a series of, e.g. temperatures, by a frequency curve constructed from the mean and standard deviation o f the series. The quesiion of the estimation of the resultant wind and scatter, when no actual wind observations arc available in the free air, is left to a subsequent paper. 2.'I'IIE TYPE O F FREQVI-A'CY DISTIIIBVTIOS IX A N'VIKD ROS1,:
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