Page:Physical Geography of the Sea and its Meteorology.djvu/479

the propriety of excluding all regions which are known to present exceptional cases to the general law. The grouping was not carried beyond lat. 60° north and south, for the lack of observations on the polar side of those parallels. The number of observations thus becoming available was 1,159,353. These were then divided simply into two classes for each belt, viz., polar winds^[1] and equatorial winds. They were then reduced to terms of a year, and the average prevalence of each wind in days deduced therefrom, as per Plate XV., and the following table:—

Polar and Equatorial Winds.

Belts.	Northern Hemisphere.					Southern Hemisphere.
	No. of Observations.	Equatorial.	Polar.	Excess in Days.		No. of Observations.	Polar.	Equatorial.	Excess in Days.
		Days.	Days.	Equatorial	Polar.		Days.	Days.	Polar.	Equatorial,
Between
0°and 5°	67,829	79	268	..	189	72,945	83	269	..	186
5 ,, 10	36,841	158	183	..	25	54,648	72	283	..	211
10 ,, 15	27,339	278	73	205	..	43,817	82	275	..	193
15 ,, 20	33,103	273	91	182	..	46,604	91	266	..	175
20 ,, 25	44,527	246	106	140	..	66,395	128	227	..	99
25 ,,30	68,777	185	163	22	..	66,635	147	208	..	61
30 ,, 35	62,514	155	195	..	40	76,254	150	204	..	54
35 ,,40	41,233	173	179	..	6	107,231	178	178	0	0
40 ,,45	33,252	163	186	..	23	63,669	202	155	47	..
45 ,, 50	29,461	164	189	..	25	29,132	209	148	61	..
50 ,,55	41,570	148	203	..	55	14,286	208	151	57	..
55 ,, 60	17,874	142	213	..	71	13,617	224	132	92	..

852. The null belts.—This plate and table reveal a marked difference in the atmospherical movements north, as compared with the atmospherical movements south of the equator. The equatorial winds of the northern hemisphere are in excess only between the parallels of 10° and 30°; i. e., they are the dominant winds over a zone 20° of lat. in breadth, while the equatorial winds of the southern hemisphere hold the mastery from 35° S. to 10° N.; i. e., they are the dominant winds over a zone 45° of lat. in breadth, while the others cover a space not half so broad. This table, moreover, shows the debatable ground between the winds, or what may be called the null belt in this general movement from poles towards the equator, and from equator towards

1. Polar winds blow toward the pole, equatorial toward the equator.