Chapter 18: Meteorology: Fronts & Frontal Depressions

Question 1

Creation / Destruction of Front

Answer 1

Frontogenesis -> converging masses

Frontolysis -> diverging masses

Question 2

Front Neutral Surface

What is? Characteristics (2)?

Answer 2

Where two fronts meet
Ground: 100 nmi
Depth: 5000 - 6000’

Question 3

Fronts

Front Types Around UK (3), Which one is all year round? Where is its frontal line?

Answer 3

Artic Front (W)
Mediterranean Front (W)
Polar Front (S+W)
Summer: Nova Scotia to Scotland
Winter: Florida to SW UK

Question 4

Polar Front Depression Formation

Formation

Answer 4

1. Quasi-stationary front: polair air N, tropical air S
2. Warm air above cold air -> depression
3. NH: CCrot -> brings warm front in front, cold behind

Question 5

Polar Front Jet Location

Why can there be confusions?

Answer 5

On map: in cold air
In reality: in warm air
because map doesn’t take into account slant of fronts

Question 6

Warm Front

Length, gradient, windspeed

Answer 6

500 nmi
1:150 - 1:180 gradient
V = 2/3 Vwind @ 3000’ = 10 kn

Question 7

Cold Front

Length, gradient, windspeed

Answer 7

300 nmi
1:50 - 1:80
V = Vwind @ 3000’ = 15kn

Question 8

Polar Front Warm Air (Middle Section)

What Cloud, vis to expect with MT? CT?

Answer 8

MT: 
Summer: Fair weather Cu, 5km vis
Winter: St, FG, Sc, < 5km vis
CT: 
Better vis, SKC

Question 9

Polar Front Depression Movement (2)

V, how long does PFD travel over a place?

Answer 9

V = 80% Vwind @ 3000’ = 12kn
Passage of PFD = 9 - 12h

Straight along isobar between cold and warm front
Warm/cold front spreads and gets bigger

Question 10

Wind Change (NH)
Through PFD, north of PFD, at warmF into Jetstream, at coldF into jetstream

Answer 10

Veering
Backing
Veering
Backing

Question 11

Secondary Low

Answer 11

Under coldF, second depression

Question 12

Temporary Cold Anticyclones

Answer 12

On both sides of PFD, cold anticyclones

Question 13

Occlusions

Answer 13

Warm/cold front meet and close up PFD
Cold occ (S): coldest air behind
Warm occ (W): coldest air in front