ILLUSTRATIONS 123 
LEGENDS FOR MODEL OF THE WARM-FRONT-TYPE OCCLUSION 
On the map :— In the vertical sections :— 
es Cumulus === Surface of Polar Front or of Tropopause 
Vv Showers ==== Internal Frontal Surface 
YJ “Upslide” Rain Occluded Frontal Surface 
Stream-lines referred to a system moving with 
Limit of Ast 10/10 > the occlusion 
iit tt Warm-sector Rain I} 11/1] Cloud-mass consisting of ice-crystals 
' oe 
; =———_— Cloud-mass consisti = 
9594959? Drizzle consisting of water-droplets 
Lower limit of ice nuclei 
Ss Stratus or Fog 
| | | | | | || \| Ordinary precipitation 
aaa 8 Warm Front ee ice 
Drizzle 
VVVVY Cold Front 
7000 Isobar Warm air 
+2?———— Isallobar 
In the high pressure wedges: 
20000065 ear! Limit of Cist 
Along the fronts: Limit of drizzle 
PL = Porar Air. TL= TROPICAL AIR 
CHARACTERISTIC POINTS OF THE OCCLUSION MODEL INDICATED IN FIG. 4. 
Vertical Section A: 
a: = Rear limit of Ast, attached to the recurving Occlusion 
eis = Rear limit of Nbst, attached to the recurving Occlusion 
= Upper retrograde Cold Front, becoming Warm Front 
a = Upper progressive Cold Front 
a; = Fore limit of Nbst attached to the original Occlusion 
as = Fore limit of Ast attached to the original Occlusion 
a; = Fore limit of Cist attached to the original Occlusion 
Vertical Section B: 
b: = Rear limit of Ast attached to the recurved Warm Front, now Cold Front 
bs = Recurved Warm Front at the ground, now Cold Front 
bs = Fore limit of Nbst, attached to the recurved Warm Front, now Cold Front 
bs = Occluded progressive Warm Front at the ground 
bs = Fore limit of the new Upslide Cloud System, formed on the occluded 
Warm Front 
bs = Rear limit of the old Upslide Cloud System, formed on the original 
Warm Front and modified by the Upper Cold Front 
b; = Upper progressive Cold Front 
bs = Fore limit of Nbst formed on the original progressive Warm Front 
Surface 
bo = Fore limit of Ast formed on the original progressive Warm Front 
Surface 
bw = Fore limit of Cist formed’ on the original progressive Warm Front 
Surface 
Vertical Section C: 
c: = Fore limit of Cist of the next disturbance 
ce. = Rear limit of Acu opacus attached to the secondary Cold Front 
¢@3; = Induced secondary Cold Front 
ec, = Fore limit of Nbst formed by the secondary Cold Front 
(Continued on next page) 
