Horizontal Vorticity and Convection Flashcards

1
Q

What are the three terms of the vertical vorticity equation?

A

1) advection
2) tilting
3) stretching

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2
Q

____ horizontal vorticity is generated at the leading edge of the cold pool, causing the cold pool to ___ along the surface

A

negative | causing cold pool to move (or spread) along the sfc

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3
Q

There is ___ pressure underneath cold air, which causes the cold air to accelerate _____

A

higher pressure | accelerate outward

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4
Q

The ambient air flows ___ the cold pool from the east, and is lifted at the ___ edge of the cold pool

A

flows toward the cold pool | lifted at the leading edge

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5
Q

In the absence of any other sources of horizontal vorticity, the lifted air is then guided ___ by the cold pool general circulation

A

guided rearward

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6
Q

In the absence of any generated ____ buoyancy produced by lifting (i.e. if the ambient air does not reach its LFC), the ambient air will not travel any farther above the cold air

A

positive buoyancy

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7
Q

When a cold pool has vertical wind shear, a positive environmental vorticity couples with negative vorticity at the edge of the gust front to develop an ____ ____

A

updraft jet

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8
Q

When the vertical wind shear vector points to the east, it signifies ____ horizontal vorticity

A

positive horizontal vorticity

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9
Q

If the magnitude of the positive horizontal vorticity associated with the ambient shear is the same as the magnitude of the negative horiz vorticity produced along the leading edge of cold air, then the air approaching the cold pool will tend to rise as a ____ ____ ___

A

vertically-oriented jet (updraft jet)

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10
Q

This produces ____ lifting at the leading edge of the cold air than from the case of no ambient vertical wind shear

A

deeper lifting

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11
Q

When the cold pool interacts with vertical wind shear, the ambient air has a much greater chance of being lifted to its ____

A

LFC

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12
Q

Evenly matched, but opposite horiz vorticity in the vorticity dipoles maintains ___ ____

A

deep updraft

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13
Q

The triggering of convective cells is favored along the ____ portion of a spreading cold pool

A

downshear

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14
Q

The strongest, most-lived convective systems will be produced when there is a strong ___ ___ ___ to balance the cold pool generated circulation

A

LL vertical wind shear

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15
Q

____ shear is important in how a storm’s updraft may evolve

A

environmental shear

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16
Q

How can you evaluate environmental wind shear?

A

plotting a hodograph

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17
Q

hodographs depict the _____ ____ of the horiz wind

A

vertical distribution

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18
Q

with hodographs, points are plotted as a function of ___ ____ and ____

A

wind direction and speed

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19
Q

with hodographs, each point represents the ____ wind at a specified elevation

A

horizontal wind

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20
Q

with a hodograph, wind vectors for each level are produced by connecting the hodograph’s ____ origin point with the ____ point

A

central origin with the plotted point

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21
Q

with hodographs, ____ shear vectors are produced by connecting two sequential points

A

layer shear vectors

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22
Q

The ___ ___ is the leading edge of the rain-cooled air in the planetary boundary layer

A

gust front

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23
Q

The gust front forms along ___ ___ of mesoscale domes of rain-cooled air that result from the amalgamation of ____-____ downdrafts from individual thunderstorm cells

A

leading edges | evaporatively-cooled

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24
Q

thunderstorm cold pools are associated with ___-___ and may actually be crudely analyzed on a synoptic surface chart

A

meso-highs (i.e. bubble highs)

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25
Q

The gust front is a ____ discontinuity

A

density

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26
Q

___, ___ surface air flows outward from the meso-high

A

cooler, denser

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27
Q

High theta-e air is uplifted ___ the outward-flowing cold pool

A

above

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28
Q

New convection may form in association with this uplift if the lifted parcels can reach their ____

A

LFC (level of free convection)

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29
Q

____ ____ ___ can play a major role in determining how high a parcel may be lifted prior to reaching its LFC

A

environmental wind shear

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30
Q

gust front passage is characterized by what 5 things?

A

1) wind shift and abrupt increase in wind speed
2) abrupt temperature drop (most of the time)
3) sharp pressure rise
4) arc cloud (if BL is moist)
5) strong VWS

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31
Q

A gust front is a ____ feature

A

mesoscale

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32
Q

The ___ ___ ___ represents the gust front

A

low cloud line

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33
Q

air lifted upward by the gust front produces a ___ ___

A

shelf cloud

34
Q

What three physical mechanisms control storm structure?

A

1) buoyancy processes
2) gust front processes
3) dynamic proceses

35
Q

What are two examples of buoyancy processes?

A

1) lapse rate (CAPE)

2) moisture stratification

36
Q

Environmental VWS affects the ability of the gust front to trigger new ___ ____

A

convective elements

37
Q

environmental VWS affects the ability of the updraft to interact with this environmental shear to produce enhanced, ___-___ storm structure

A

quasi-steady

38
Q

for the storm, shear is relative to the ____ of the storm

A

motion

39
Q

a storm travelling at the speed of the mean vector wind (MVW) automatically develops an enhanced ____ _____ into its updraft

A

inflow of BL air

40
Q

the LL air has a strong component of ___ ___ toward the approaching storm

A

low-level

41
Q

the magnitude of the inflow can be properly matched to the magnitude of the ____ updraft

A

buoyant updraft

42
Q

in the absence of suitable shear, the inflow will be _____ to sustain the vigorous updraft that might result from large thermal instability

A

insufficient

43
Q

what are 2 examples of gust front processes?

A

1) strength of cold pool

2) strength of LL VWS

44
Q

What are 2 examples of dynamic processes?

A

1) strength of 4-6 km AGL VWS
2) development of rotational (helical) updrafts and associated favorable vertical pressure gradients on the updraft flank

45
Q

With an ordinary cell, ____ more important in maintaining updraft than ___ processes

A

buoyancy | dynamic

46
Q

with supercells, ____ processes are more important than ____ in maintaining updraft

A

dynamic | buoyancy

47
Q

vertical wind shear produces ____ ___ ___

A

horizontal vorticity tubes

48
Q

horizontal vorticity tubes are incorporated into a ____ ____ and tilt ____

A

thunderstorm updraft | tilt vertically

49
Q

the updraft begins to rotate in the same sense as the ____ ____ (cyclonic or anticyclonic)

A

vertical vorticity

50
Q

updraft intensity is _____ within rotating cores

A

maximized

51
Q

precipitation loading in updraft weakness between rotating cores produces a ____

A

downdraft

52
Q

a downdraft separates the ____ updraft from the ___ updraft

A

cyclonic | anticyclonic

53
Q

____ ____ occurs as each updraft sustains a separate storm cell

A

storm splitting

54
Q

what is the first stage of storm splitting?

A

cyclonic and anticyclonic updrafts

55
Q

what is the second stage of storm splitting?

A

the initial storm now splits into two

56
Q

a rotating updraft can cause the storms motion to significantly deviate from the ___ ___ ___

A

mean vector wind (MVW)

57
Q

with a cyclonically-rotating updraft, the Bernoulli effects produce ___ pressure on the ___ side of the cyclonic updraft in the mid-troposphere

A

low (high) | right (left)

58
Q

with a cyclonically-rotating updraft, cyclonic storms move to the ____ of the MVW

A

right

59
Q

with a cyclonically-rotating updraft, ___ supercells are favored within veering vertical wind profiles

A

SR supercells

60
Q

cyclonically-rotating storms develop a ____ motion (right-mover) relative to MVW

A

rightward motion

61
Q

with a anti-cyclonically-rotating updraft, the Bernoulli effects produce ____ pressure on the ____ side of the anticyclonic updraft in the mid-troposphere

A

low (high) | left (right)

62
Q

with a anti-cyclonically-rotating updraft, anticyclonic storm moves to the ___ of the MVW (SL supercell)

A

left

63
Q

with a no-shear ordinary cell, the gust front rapidly ____ the storm

A

outruns

64
Q

with a no-shear ordinary cell, the storm is left totally _____ over BL cold pool

A

entrenched

65
Q

with a moderate-shear multicell, the storm will move downshear at roughly the same speed as the _____ between the sfc and 6 km altitude AGL

A

MVW

66
Q

with a moderate-shear multicell, new cell growth is enhanced along the ____ portion of the gust front

A

downshear

67
Q

new cell growth along the downshear portion of the gust front ____ relative flow into the newly-developed cells

A

increases

68
Q

new cell growth along the downshear portion of the GF ____ the length of time cells stay in the vicinity of strong LL convergence zone and associated lifting near GF

A

increases

69
Q

for strong-shear supercells, rotation develops on the ___ ___ ___ ____ due to vertical tilting of pre-existing horizontal vorticity within the sheared flow

A

flank of the updraft

70
Q

for strong-shear supercells, if the VWS extends through the middle-levels of the storm, the rotation dynamically induces a ____ pressure anomaly in the middle troposphere

A

negative (low) pressure

71
Q

What does NPA stand for?

A

Negative pressure anomaly

72
Q

the NPA produces a strong _______ pressure gradient which accelerates BL air violently upward

A

non-hydrostatic

73
Q

rotating updrafts associated with mid-level NPA’s are _____ and remain ____ after the storm moves into a more stable environment

A

long-lived | remain vigorous

74
Q

rotation also causes storm motion to deviate from the ____

A

MVW

75
Q

_____ shear favors storm splitting as NPA

A

unidirectional shear

76
Q

____ shear forms at mid-levels within rotating updrafts on both right (cyclonic) and left (anticyclonic) side of original storm

A

unidirectional shear

77
Q

____ shear has split cells that are nearly identical rotate in opposite directions

A

unidirectional shear

78
Q

____ shear has a climatologically favored veering shear pattern

A

curved shear

79
Q

___ shear has strongly veering winds that favor strongly right-moving cells with cyclonic rotation.

A

curved shear

80
Q

With curved shear, left moving anticyclonic cells are ____ _____

A

not favored