554 THE GENERAL CIRCULATION 
inferred from the classical work of Dines [18] in which 
was pointed out the good correlations between tem- 
perature and pressure in mid-troposphere and at the 
tropopause. The strength of the circumpolar whirl is 
diminished with decreasing elevation. Below the level 
of 700 mb the circumpolar vortex begins to be somewhat 
obscured by the appearance of a more cellular character 
of the general circulation, and by the time we reach 
maps at sea level (Figs. 5 and 6) the “centers of action” 
tale on considerable cellular character. Noteworthy is 
ie 
[fir rey 
Lie ESS ON LS Dye 
SOK ONS 
isey Va Lh 
Ae £& Na 
SP Pes? PS 
WN v.Kte Oe 
WN SS Zi Va My, 
Sas 
~~”, 
EPROFILE So 
i 90° 
uw 105) 
We 
JANUARY 
) 
WY 
| 
[~ beet tL . 
Xt \ 3 foe ZY, 
Ss SS suns Ds zs 
@m PROFILE 
S 90° 60° 50° 40° 30° LAT 
& 25 
Fie. 5.—Normal pressure distribution at sea level (below) 
and normal contours at 700 mb (above) for January. Profiles 
inserted. Dashed lines at 700 mb are isotherms for every five 
centigrade degrees. 
the emergence of easterly winds north of the subpolar 
lows and in the subtropics. The easterlies of the polar 
regions are for the most part shallow phenomena gen- 
erally below 3 km, but in low latitudes, particularly in 
summer, easterly winds are very deep and extend well 
into the stratosphere. 
The circumpolar vortex in the upper troposphere and 
lower stratosphere, while primarily zonal in character, 
undergoes gentle north-south undulations so that the 
isobars have a roughly sinusoidal character. The ridges 
and troughs aloft have their reflections at the surface 
e4 
{| Ys 
302 LATNY 
Ay 
AIS 
6 
4, 
EN S 
JEN 
SONS 
Dh Se 
ean 
Se eS 
By oN 
7 
Fig. 6.—Normal pressure distribution at sea level (below) 
and normal contours at 700 mb (above) for July. Profiles 
inse=ted. 
