Fronts

Question 1

What is a front

Answer 1

A place where air masses meet

Question 2

Developing front symbol

Answer 2

Triangles with dots

Could also be called frontal-genesis

Question 3

Decaying front symbol

Answer 3

Triangles with crosses

Could also be called frontolysis

Question 4

Quasi front

Answer 4

Stationary front

Little movement, 5 kts

Caused by parallel isobars and geostrophic wind running parallel to the front

Very unstable

Doesn’t last very long

Question 5

Polar front

Answer 5

Marks the boundary between polar maritime and tropical maritime air masses

Boundary between polar and Ferrell cells

Varies due to seasons and land masses
Average position is 50*N/S

Question 6

Intertropical front

Answer 6

ITCZ

Zone of converging air-masses due to trade winds

Question 7

Mediterranean front

Answer 7

Only in winter

Warm winds from the south meet colder winds from the European land mass

Question 8

Arctic front

Answer 8

Only forms in winter, the temp is so low that a pressure gradient is formed

Can be very faint
Can create an arctic front jet stream
N America/america

Question 9

Frontal surface

Answer 9

Slopping boundary between air masses

Approx 3-5km long

Question 10

Summer polar front

Answer 10

Canada to over Scotland

Around 65* max north

Question 11

Winter time polar front

Answer 11

Florida to SW uk

Can be as low as 35* max

Question 12

Polar front depression

Answer 12

A low is created off the coast of Florida which could be caused by high winds.

The cold air undercuts the air, making the waves bigger down the front

Question 13

Other names for PFD

Answer 13

Westerly waves
Frontal waves
Westerly situation

Question 14

Speed of the fronts in a PFD

Answer 14

Cold, same speed as system

Warm, 2/3rds of the speed

Question 15

To establish the speed and direction of a PFD

Answer 15

Use the first 2 isobars

The direction they are pointing is the direction the front is moving

The spacing between 2 isobars is the speed

Question 16

Ahead of a warm front

Answer 16

500 - 800km/ 500 -600nm
Wind - veers SW, backs in the Southern Hemisphere 
Temp/dp - steady low 
P - slow then quick decrease
Cloud - ci cs, as, ns,st
FEW-OVC
Precipitation - DZ,RA 200nm
Viz-decrease to poor fg 
Turb- light to mod

Question 17

At the warm front

Answer 17

200nm
Wind - sharp veer/back in Southern Hemisphere 
Temp/dp - sudden increase 
P- slow decrease 
Cloud - st/ns
Precipitation - ra/dz poss FZRA
Vis-poor, poss fg 
1:150, gentle slope

Question 18

In the warm front

Answer 18

Wind - steady W
Temp/dp - steady warm 
P - slowly decrease 
Cloud in winter - BKN/OVC, st,Sc
Cloud in summer - fairwx cumulus 
Precipitation - RA/DZ
Vis-winter-poor, fg 
Summer - good SkC Avrg 5-6km
Possible light to mod rime ice 
Possible carburettor ice at high levels

Question 19

At the cold front

Answer 19

50-100m/300nm/400km
Wind - sharp veer/back in Southern Hemisphere 
Temp/dp - sudden decrease 
P-decreases then slow increase 
Cloud - BKN/OVC, convective cloud 
Precipitation - shra/ts/gr/gs
Vis-good outa sh 
Mod to severe turb and icing 
Steep incline 1:80

Question 20

Behind a cold front

Answer 20

Wind - Slight veer/ back in Southern Hemisphere 
Temp/dp - steady low 
P-slowly rising 
Cloud-BKN,higher base, isol cu cb 
Precipitation- sh/shra/ts/gr/gs
Vis-good out of sh

Question 21

Secondary depressions

Answer 21

Form within the circulation of a main primary depression
May be caused by a localised effect like orographic uplift
Weather conditions are more severe

Question 22

Frontal secondaries

Answer 22

Secondary depression that forms on the trailing cold front

Question 23

What happens to the altimeter on passage of a PFD

Answer 23

Thinks you’re higher on passage of a warm front

Thinks your lower on passage of a cold front due to higher pressure

Question 24

What happens to pressure just before the cold front

Answer 24

Sudden reduction

Question 25

Occlusion

Answer 25

Cold front catches up with the warm front

All clouds are pushed together

Question 26

Warm occulusion

Answer 26

Typically occurs in winter
Coldest air is ahead of the warm front
Forces cold above it
Rains before the warm front passes

Question 27

Cold occlusion

Answer 27

Coldest air is behind the cold front and cuts under warm air
Typically forms in winter
Rains before and after the warm front

Question 28

Biggest danger with occlusion

Answer 28

EMB cbs due to the clues being pushed together

Question 29

Non occluded PFD

Answer 29

Normal PFD

Question 30

Back bent occlusion

Answer 30

The occlusion bends backwards
Will continue to move with the depression
Stronger worst weather
Jet stream cuts through