DYNAMIC ANTICYCLONES AT 
SURFACE MAP 
Nn FicdS 
Fig. 3. PRESSURE DISTRIBUTION AT SEA LEVEL 
(mb), FEBRUARY 38, 1937, 8 A.M. 
Fic. 5. PRESSURE DISTRIBUTION AT 5,000 FEET, 
FEBRUARY 3, 19387, 8 A.M. 
Simmers* using isentropic analysis, a warm 
upper-level anticyclone over Texas and a cold 
one moving down from Canada amalgamated. 
The warm anticyclone built up from middle to 
high levels through a process of isentropic mix- 
ing which transferred air across isobars 
(“banking effect’? described by Namias in his 
chapter on Isentropic Analysis). The resulting 
convergence caused the surface pressure to 
continue to rise, although the cold anticyclone 
was being dissipated by surface heating. This 
was in May and there was no evidence the 
warm anticyclone gtew from the cold one, but 
*R. G. Simmers, in: Fluid Mechanics Ap- 
plied to the Study of Atmospheric Circulation, 
Part I, Pavers in LES. Oceanogr. and Met., 
vol. 8. 1938. 
\ 
DECREASE IX FIRST S000 FEET 
Fie. 4 
L 
Fic. 4. PRESSURE DECREASE IN FIRST 5,000 FEET, 
FEBRUARY 38, 1937, 8 A.M. 
Fic. 6. PRESSURE DISTRIBUTION AT 14,000 FEET, 
FEBRUARY 3, 1937, 8 A.M. (The dotted cir- 
eles show ‘the position of the surface 
Highs ) 
rather their paths just happened to intersect. 
Probably there are various possible types of 
anticyclogenesis. ; 
Cyclones also occur in warm and cold types. 
The usual open warm-sector or freshly-oc- 
but fre- 
quently an occlusion develops into a deep 
slowly-moving vortex without fronts but cloudy 
and with precipitation; soundings will show 
the core to be colder than the surroundings up 
to hizh levels, even to the stratosphere, which 
may be sucked down and warmed, thus help- 
ing to maintain the surface low. These cold 
eyclones occur particularly in the regions 
where cyclones usually have reached the oc- 
cluded stage, in the higher latitudes of the 
cluded low contains a warm core, 
