G9G MR ROBERT COCKBURN MOSSMAN ON 



In spring and summer there is a well marked tendency for warm weather if the 

 wind be calm or from the S.E. or N.W. During autumn and winter, low temperatures 

 are experienced when these winds occur. The explanation is probably to be found in 

 the considerable stretch of land traversed by S.E. and N.W. winds before reaching 

 Edinburgh. During winter the temperature over these districts is low, owing to 

 terrestrial radiation, while in summer the temperature inland is high. 



Humidity. — The dampest winds are those from the E., N.E., and S.E., which blow 

 off the North Sea, calms also having a high percentage of humidity. The driest wind 

 is the N.W., except in winter, when the S.W. takes its place. The S.E. wind is a dry 

 one in the early summer. 



Vapour in a Cubic Foot of Air is at a maximum with S.W. winds and at a 

 minimum when the direction is N. The S. wind has a remarkably large amount 

 of water vapour present in July, August, and September, this being doubtless clue to 

 its high temperature. 



Sunshine is most prevalent with winds from the N.W., W., and N., while but little 

 is recorded with winds from an easterly quarter. When the air is calm during winter, 

 sunless weather predominates, but fine weather prevails in summer with a calm 

 atmosphere. 



General Remarks. — The climatic features of the various winds at Edinburgh depend 

 in no inconsiderable degree on whether they have blown over the land or over the sea ; 

 land winds being sunny, and dry at all seasons, warm in summer and cold in winter. 

 Sea winds, on the other hand, are cold, clamp, and sunless at all seasons of the year, 

 the conditions varying according to the relationship existing between the temperature 

 of the land surfaces and that of the contiguous expanses of water. For example, in 

 spring and summer when there is little difference between the temperature of the North 

 Sea and its western shores, a rapid increase of temperature being then in progress, the 

 easterly winds at Edinburgh are comparatively sunny and warm ; but in autumn and 

 winter when the above conditions arc reversed, the weather experienced is cold, dull, 

 and humid. 



On the General Climatic Characteristics of the Months at Edinburgh. 

 We have referred to the fact that the phenomena which are, in the aggregate, 



designated " weather," depend on the distribution of pressure over Western Europe at 

 the time. When the barometer, for example, is high to the north of our islands and 

 low to the south we have easterly winds ; when the reverse conditions of pressure j>re- 

 vail, winds from the west predominate. The polar and equatorial air currents, as has 

 been shown, are accompanied by totally different phenomena as regards temperature, 

 humidity, rain, sunshine, and so on. 



An examination of the data which are graphically projected on the plates clearly 

 shows that certain definite weather types tend to recur from year to year at approxi- 



