26 BULLETIN 1191, U. S. DEPARTMENT OF AGRICULTURE. 
TABLE 3.—Total monthly atmospheric movements and prevailing direction as 
recorded at Point Reyes Light. 
14,845 NW. 
[Miles per month.] 
fy | | | 
Month. ESO) 1892-1918 
onth 1917 1918 average, 
w =e = = + See ae SWATH BSF SS z 
January | 12,864 NW. | 14,134 NW. | 12,543 NW. 
February 14,821 N. 15,368 NW. | 12,878 NW. 
Maron. 756.000 AT AG. Babs tae oe 20,638 NW. | 11,333 NW. | 15,580 NW. 
CT ane eae 14,454 NW. | 18,617 NW. | 16,702 NW. 
2 Et aes es | 21,369 NW. | 23,237 NW. | 195194 NW. 
Se A | 22,719 NW. | 16,133 NW. | 19,602 NW. 
SERS SR EERIE De te EE ORES, Cam | 14,944 NW. | 16,861 NW. | 1€,522 NW. 
ATPASE. 0 eee | 11,586 NW. | 13,140 NW. 14,545 NW. 
September SganevaSocnpenna2heh.| 190443 NW. | 9, 819 NW. | ie Gree 
October 9,509 NW. | 127923NW. | 12,698 NW. 
November | 9,861 NW. | 11,616 NW. | 11,776 NW. 
RE tv speremn cornea apenas BEE | 117052.N.- | 12831 NW. | 127133 NW. 
Mean 205 222: 22 <s..va. ee)! | 14,688 NW. | 14,667 NW. 
TasLe 4.—Total monthly atmospheric movements and prevailing direction as 
recorded at San Diego. 
[Miles per month.] 
1892-1918 
Month. | 1917 1918 average. 
i es ee 
Tee ip geo aT Se EL ee ee ap ee 2 3,853 E | 3,982 E. _ 8,928 variable. 
ES SE et RE a SE ae ee eae AES, BP Pa 3,972 NW 4,579 W. 3,903 NW. 
Lb Cs RAS 5. 5. cia ee RR Se SS TRA ese 2 2 PS. 4,645 NW 4,464 NW. | 4,582 NW. 
A ete a ee reser. sien bc Mee cca ctued do abay 5,299 W. 4,539 W. 4,546 NW. 
Ear tse oi wins oe cates a tea neta sas ee anaet ones = 5,659 SW. 5,325SW. | 4,763 W. or SW 
Semacet i eae ees: De. BAS st a 4,295 W. (| 4,697W. | 4,376 W. or SW 
11 abel REG OP eR SAY PE GE Or at Soarsae 4,342 W 4,864NW. 4,354 NW 
ge RSS Sa ee oa vse 8 | AA) $F A ee Te 4,661NW. 4,901 NW. | 4,261 NW. 
SE Re ea PP Ma be” Rap ere a’ Be 4,273NW. | 4,524 NW. | 4,130 NW 
IP ie ne a SAREE RAS aie Sa a BELG TNS | 3,749NW. | 4,172NW. | 3,920NW. 
TL ga ae oe ee a ee ee GY 2¥ Pe Poa Ca | 3,329NW. | 4,186 NW. | 3,703 NW. 
io eae gee ALAS Cand BES hy A eee 3,075 NW. | 3,888 E. 3,746 NW. 
or TS ACE ae eR a a © Sy el | 4,263NW. | 4,510NW. | 4,184 NW. 
As noted before, even a light breeze causes ripples that splash 
over the kelp, keeping it wet and cool, but these ripples are soon lost 
in a thick bed of kelp, and perhaps it is because of this fact that the 
largest and most virgorous plants always occur near the edges of 
the bed, while dead and decaying material appears first in the 
heavy mats. 
Strong winds are continually recharging the water with air. 
Setchell (7) states that kelps require a great amount of air; that 
some forms, such as Postelsia, grow only in the surf on the most 
exposed points, where they are continually bathed in spray. One of 
the first things discovered in growing kelps in aquaria is the necessity 
of working an abundant supply of air into the water. The air 
worked into the ocean water by the action of the wind, seen in the 
formation of “ whitecaps,’ is mainly brought to the plants by 
surface drift. In very windy weather, however, the kelp fronds are 
whipped about and oftentimes fragments and even whole plants are 
torn away. 
