86 CALIFORNIA ACADEMY OF SCIENCES. 



ceases very suddenly. The temperature is unusually low» 

 See Plate V. 



SUB-NOEMAL TYPE. 



This type is marked by a succession of days when the 

 pressure is moderately low, and below the normal over a 

 large area. The isobars are broken up, are wavy or enclose 

 several subsidiary low areas, with an absence of any de- 

 cided gradients. This type prevailed from February 26th 

 to March 4th, and from April 5th to 7th. Kain at intervals 

 occurs, frequent local storms, and thunder storms are re- 

 ported. Occasionally a gale, but local in character, does 

 coQsiderable damage. The winds are variable, and the 

 weather cool and cloudy. 



It might be well to add that the changes occurring in the 

 cyclonic types follow a general principle that a disturbed 

 equipoise recovers itself in proportion to the intensity and 

 rate which the disturbance has originally developed. The 

 greater the high, the greater the depth of the low which 

 follows, and if the change is sudden, the appearance of the 

 opposite condition is sudden. In meteorology, as in me- 

 chanics, these vibrations of the disturbed equipoise are lia- 

 ble to continue for some time in waves of gradually decreas- 

 ing length before coming to rest; and the observance of this 

 principle enables us to say that a disturbance is not defi- 

 nitely passed although the synoptic charts give but little in- 

 dication of its recurrence. 



The dry season demands only the briefest consideration,, 

 having but one general characteristic — high pressure over 

 the sea and low over the land. The tjqoe of the dry season 

 has about the sameness of the weather which accompanies 

 it. The high is greatest and most persistent over the ocean 

 and north Pacific coast, and lowest from Arizona to Nevada 

 including eastern California. Almost the only peculiar fea- 

 ture of the type is the occasional low over the central val- 

 leys of California. 



