412 TRANSACTIONS OF THE 



The next distinct type is the 



South Pacific Anti-Cyclonic, 



Which appears as a moderate high along the southwestern California 

 coast. It is peculiar on account of the rains which accompany it, being 

 one of those types which bring out many inquiries from those having and 

 observing barometers, asking the question, how it is that we have rain 

 with so high a barometer. It creates isobars somewhat perpendicular to 

 the coast, bringing in the rain-bearing southerly winds at San Francisco. 

 It is noteworthy that any type exhibiting isobars perpendicular to the 

 coast line is almost sure to bring rain, while if the isobars are parallel to 

 the coast fair weather follows. This type was in existence from March 

 thirty-first to April second, and from April seventh to seventeenth. During 

 its prevalence a faint low may exist in the north Pacific. Rain occurs in 

 the interior California valleys and northward; also in the vicinity of Los 

 Angeles. Should the general pressure fall considerably below the normal, 

 but with the relatively high barometer continuing in the same region, gales, 

 with thunder and hail storms, are frequent in Southern California. The 

 winds are not strong north of San Francisco, except when the barometer 

 becomes very low, and such cases are few. This type disappears by the 

 movement of the high along the coast into Oregon, and ceases very sud- 

 denly. The temperature is unusually low. See Plate V. 



Sub-Normal Type. 



This type is marked by a succession of days when the pressure is mod- 

 erately low, and below the normal over a large area. The isobars are 

 broken up ; are wavy, or inclose several subsidiary low areas, with an 

 absence of any decided gradients. This type prevailed from February 

 twenty-sixth to March fourth, and from April fifth to seventh. Rain at 

 intervals occurs, frequent local storms, and thunder storms are reported. 

 Occasionally a gale, but local in character, does considerable 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 prin- 

 ciple 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 meteor- 

 ology, as in mechanics, these vibrations of the disturbed equipoise are 

 liable to continue for some time in waves of gradually decreasing length 

 before coming to rest; and the observance of this principle enables us to 

 say that a disturbance is not definitely passed, although the synoptic charts 

 give but little indication 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 type 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 feature of the type is the occasional low over the central 

 valleys of California. 



Rain is almost entirely absent when this type becomes perfectly estab- 

 lished, and only occurs in light showers in Oregon and Washington Terri- 

 tory, when the high happens to drop down well on the California coast, 

 creating a condition similar to that of the " South Pacific Anti-Cyclonic 



