1921] Brooks : Mountain Climates. 245 



England, in exceptionally heavy thunderstorms. The cause 

 of this heavy rainfall is the great amount of moisture in 

 the air. Saturated air at 80° F. contains twice as much 

 moisture as the same volume of saturated air at 60° F., and 

 nearly four times as much as at 40° F. It is by the elevation 

 of air and its consequent cooling that clouds and rain are 

 formed. If saturated air is cooled from 80° F. to 60° F. it 

 will set free twice as much water, that is, the rain will be 

 twice as heavy, as if it were cooled from 60° F. to 40° F. 

 The number of days — 173 — at Singapore is almost the same 

 as at Richmond (170), and in Perak, although the total fall 

 is greater, the average number of days is only 156. A 

 " rain-day " is defined as a day on which a measurable 

 amount of rain, generally • 01 inch or more falls. 



There is some attempt at the development of a rainy 

 season in the Straits Settlements, but it differs in different 

 parts. At Singapore the rainiest months are November to 

 January, and the least rainy — one can hardly call them 

 dry — May to September. In Perak September to November 

 are the rainiest months, January and February the least 

 rainy. Even the relatively dry months however exceed six 

 inches (160 mm.) in their rainfall, a total representing an 

 unusually wet month in England. 



Some of the individual falls are exceedingly heavy, 

 Singapore having experienced more than 7 inches (175 

 mm.) in a day on at least two occasions, while Perak has 

 reached the total of 13-8 inches (346 mm.) in 24 hours. 

 But at a mountain station we may expect the falls to be 

 less heavy and more continuous. 



There is one point in which mountain climates in the 

 tropics are unfavourably situated, and that in the unequal 

 division of the rainfall between the day and the night, owing 

 to the daily variation in the level of the clouds. Tosari, 

 the health resort of Java previously referred to, has an 

 annual rainfall during the day of about four times as much 

 as that during the night, and this peculiarity is probably 

 shared by other mountain stations in the tropics of a similar 

 height. 



6. Storms. 



Tosari is very subject to severe storms from the south- 

 west, but these are local only, being due to the peculiar 

 nature of the topography of East Java, where a long funnel- 

 shaped valley conducts the winds with accumulated force 

 straight to the settlement. An open isolated peak should 

 be much better situated in this respect, and should rarely 

 experience more than a strong breeze. 



