SAS a ee se 
and the Velocity of the Wind. 349 
The other component of the resistance, therefore, contrary to 
the direction of the radius, in which the velocity of motion is 
D,7, is represented by 
oan Dr __2(nsinl+-u) (D,r)? 
— One ru cost ; 
This expression is always positive, but it applies only to the 
part near the earth’s surface, where the one component of mo- 
tion is toward the center of the cyclone. 
_With this value of F (6) gives, neglecting 4u in comparison 
with nsin/ in the value of F’, 
‘__@ (2nsinI+u)v cos t/ (Dr)? p 
8 nrc reipenceernonn tase eperemennraae: uP lb «by area yt ped OB, 
(8) S g 10500 \"* @eos a) p”? 
_@ (2nsinl+u)v sect p 
Ais 10500 de 
since by the definition of 7 we have 
(9) tan im : 
Since the unit of time is one hour in the expression of G, we 
_ AER pat g=36002 X32°2 ft. 79040 miles, 
With this value of g, putting a2=100 miles, and with the value 
: fo] 
tion in terms of the radius, which is 0262, we get from (8) by 
the expression of Gin (1). At the earth’s sur- 
of n, the angular rotatory Mati per hour of the earth 
3 p 
utting ——— 
ing 
face the factor - becomes unity. 
8. If the internal and external parts of the cyclone had the 
same temperature, the strata of equal pressures would be par- 
allel, or equidistant, and D,A would be a constant for the same 
place at all altitudes, and G would be proportional toS. But 
m order to keep up the motive power of the cyclone there 
must be a difference of temperature between the interna] an 
external parts, and this causes an increase or decrease in the 
value of D,A with the altitude, and consequently by (5) an in- 
crease or decrease of G in a greater ratio than that of p, other 
things remaining the same. In an ordinary cyclone, in which 
the temperature is greatest, and consequently the density least, 
in the interior of the cyclone, the value of G increases in a less 
ratio than p, and hence in order to satisfy (8) v cos? must have 
a less value above than below; but the reverse of this is true 
where the density is greatest in the interior at the same pres- 
sure, as in the polar hemispherical cyclones, and hence the 
mean constant motions of the upper strata of the atmosphere 
relative to the lower ones is eastward in all latitudes. 
