226 



RELATIVE HUMIDITY, 



The relative humidify is greatest at the equator, and diminishes 

 towards the i)oles. It is at its maximum over the sea, and diminishes 

 as we go inland, being lowest on the leeward side of high mountain 

 ranges, and in places remote from the sea, as well as those most exposed 

 to drying winds. 



J'f.r. J[)e^0e-S of Tempera-ttiT'e', (-P) 



Eclative Hnmiclity at different temperatures, the I Eelativo Iluinidity at fixed tempcratnrcs, the dif 

 ditierence between wet and dry bulb thenuoine- ference between wet and dry bulbs being vari- 

 ters being constant. | able. 



With reference to the amount of rain-fall, it has been observed, as a 

 general rule, that the quantity falling on high grounds, rising by easy 

 slopes, exceeds that at the level of the sea ; but if the elevation is ahrupt, 

 the quantity is less. 



The effect of lieat being to increase the capacity of the atmosphere 

 for holding aqueous vapor in suspension, and that of cold to reduce it, 

 or, in other words, to bring this vapor to a degree where it could no 

 longer be held, it follows that a marked difference should exist between 

 the temperatures at which precipitation occurs in winter and in -sum- 

 mer, and that while the absoluie humidity in the warmer months is very 

 much greater, in summer the relative humidity is less. This may bo 

 illustrated by a few comparisons from foreign observations with others 

 made in this countrv. 



Absolute Moisture at several foreign stations. (Millimeters.) 



