THE METEOROLOGY OF EDINBURGH. 



83 



Rainband. 



Days. 



Rain fell Days. 



Per cent, of Cases 



followed by Rain within 



24 Hours. 



o-o 



44 



9 



20 



0-5 



146 



44 



27 



10 



347 



146 



42 



1-5 



256 



143 



56 



2-0 



123 



93 



76 



2 "5 and upwards 



66 



60 



91 



It will be seen that there is a regular rise in the frequency of rainfall with an 

 increasing rainband. The principal drawback to the forecasting value of these 

 spectroscopic indications lies in the fact that nearly two-thirds of the readings are 

 normal. It will be seen on reference to the Table that the chances of rain or no rain, 

 with values corresponding to l'O and 1'5 on our mental scale, are pretty evenly 

 balanced. Under such circumstances the observer must turn to his other instruments 

 for guidance in framing his prognostications. Many cases occurred during the ten years 

 under review when a thick rainband was observed with a clear sky, and a thin one with 

 a cloudy sky, the accompanying weather being wet in the one case and dry in the 

 other. One point specially noticed is that days on which hail fell are characterised by 

 low rainband values, while the same may be said regarding days with snow. An 

 elaborate investigation into the whole subject was commenced some time ago, but it has 

 not been found possible to include the results in this paper. 



Solar and Terrestrial Radiation. 



The following tabular statement shows the more prominent results deduced from the 

 reduction of the daily observations taken in the south side of Edinburgh during the 

 nine years 1888-96. The solar radiation thermometer is at a height of four feet above 

 the ground, and the terrestrial radiation at a height of a quarter of an inch over short 

 grass. 



It will be seen that solar radiation is at a maximum in May, and at a minimum in 

 December ; while terrestrial radiation is at a maximum in November, and at a minimum 

 in June. The greatest excess of sun over shade temperature occurred on March 27, 1892, 

 viz., 76° '8 ; while on May 22, 1890, the grass minimum fell 12°'6 below the minimum 

 in shade. A few cases have been observed when slight inversions of the normal 

 condition of affairs took place, the air at the time being nearly saturated and the sky 

 densely overcast. The maximum excesses of sun over shade were observed in spring or 

 early summer on days when showers and bright sunshine alternated. 



