Ch 18 - Fronts And Frontal Depressions Flashcards

1
Q

Frontogenesis

A

The formation of a front

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2
Q

Frontolysis

A

Dissipation of a front

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3
Q

Front

A

Narrow area where a front is passing through that covers a few miles

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4
Q

Transitional Zone

A

An area where a front is moving though can be 100’s of miles - ITCZ

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5
Q

Quasi-Stationary Front

A

Very little movement (5kt)

Flowing parallel to the friction layer

Could interact with the surface and create clouds, SHRA and DZ

Usually there is no weather but depends on the level of instability

Can be around for long periods of time

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6
Q

Polar Font

A

Where the polar air and the warmer Ferrell masses meet at ~50 degrees N/S

Tropical maritime and polar maritime

Always there

Circumnavigated the globe

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7
Q

Mediterranean Front

A

Usually occurs in winter

Where the is low pressure moving from east to west

Can be strengthened by the wind coming off the N. African coast

Because the ocean temp is higher than the land, there is low pressure on the sea, strong wind coming off the land which can lead to MEDICONES - storms along the front

Usually has increment weather

In the summer, the ITCZ moves north and brings with it high pressure - Med Weather

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8
Q

ITCZ

A

The intertropical convergence zone (the heat equator)

A transitional area over a very large area

Is the meeting of air masses that causes the trade winds (a low pressure belt)

North in summer and further south in winter

Can bring with it intense TS and TRS that go up to 45,000ft

It moves

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9
Q

Polar Front Examples

A

Between 40-60 degrees north and south

Summer it can be found over new found land or Norway and north Scotland

In winter it moves down towards Florida or the SW UK

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10
Q

A Polar Front depression

A

Forms at the polar front when the sub tropical warm air starts to mix with the cooler polar air

Starts as a disturbance and forms into a wedge shaped depression

(Westerly waves also known as the westerly situation + travelling lows)

Comprised of a Warm front, Warm sector and a cold front

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11
Q

Warm Front

A

Polar air in front with tropical air behind

Can bring with it frontal fog

Ci seen first, slowly gets worse and worse until a NS

May see Virga

Will have Ra and decreasing vis as it passes

Spans over 6/700nm with speeds of 2/3 of the 2000ft wind

1:150 slope

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12
Q

Warm Sector

A

Can have ST, FWX CU low level cloud with little vertical development

Usually no RA

Can have DZ, -RA and Fog in winter

If cT: little cloud development with clear good WX

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13
Q

Cold Front

A

Has a cold nose

Possible TS

CU CB EMB CB NS AS

Gusts as it approaches, RA

1:50

50/100nm

Travels at 100% of the 2000ft wind

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14
Q

SPD and Direction of a polar front depression

A

Isobars extended out from the warm sector will show you the direction

Speed can be determined by using the geostrophic wind scale in the corner

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15
Q

Depression Hazards: Warm Front

A
FzRA
Low cloud
Icing in cloud
Poor Vis.
Cloud/RA/FG
Aquaplaning on RW
CAT around jet stream
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16
Q

Depression Hazards: Cold Front

A
Squall line of TS
SEV TURB and ICING 
CBs
Lighting from TS
Wind shear
Poor vis 
\+Precip
CAT around Jet Stream
Aquaplaning on wet RW
17
Q

Frontal Secondary

A

The beginning of a polar front depression in the wake of the original PFD

18
Q

Cold Temporary Anti-Cyclone

A

A relatively high pressure day or so respite between 2 polar front depressions

Very typical of the uk

Only between 2 PFDs

19
Q

Occlusions

A

When a cold front catches a warm front and they mix

Brings with it worse weather and double the portion of cloud and precipitation

20
Q

Warm Occlusion

A

More often in winter

Rain falls ahead of occlusion

Where the cold mP air mass rises up over the top of the colder more dense cP

21
Q

Cold Occlusion

A

More often in summer

We’re the coldest mP (cold front) undercuts the relatively warmer Warm front mP

Most of the rain will fall ahead of the occlusion