Final Exam Flashcards by McKenna Stanford

Define Cyclogenesis. (Don’t worry, it’s a short definition.)

The formation of a cyclone.

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Define Cyclolysis. (Again, a short definition.)

The decay of a cyclone.

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Conceptual frameworks for cyclogenesis are often based on (vorticity/pressure) rather than (vorticity/pressure).

vorticity

pressure

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Pressure tendencies, height tendencies, and geostrophic vorticity tendencies are coupled through the ______________ __________ relationship.

geostrophic wind

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Pressure, height, and geostrophic vorticity tendencies are intrinsically linked.

An increase in surface vorticity is associated with height and pressure (falls/rises).

A decrease in surface vorticity is associated with height and pressure (falls/rises).

falls

rises

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We can diagnose cyclogenesis using the vorticity equation, but we ignore which 3 terms?

friction
tilting
solenoidal

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Lower tropospheric (stretching/compression) is a mechanism for voriticty generation and cyclogenesis. This is the same as (ascent/descent).

stretching

descent

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Answer the following questions in regards to an example of cylogenesis.
An upper-level trough and associated area of (CVA/AVA) and (ascent/descent) overtake a low-level frontal zone. The low-level frontal zone is characterized by (high/low) initial (relative/absolute) vorticity. (Stretching/Compression) associated with the upper-level trough most effectively generates vorticity along the front. This is due to the (absolute/relative) vorticity multiplier in the vorticity equation.

CVA
ascent
absolute
stretching
absolute

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Assuming hydrostatic balance, define pressure. (easy)

The weight of the overlying atmosphere.

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Surface pressure changes are due to integrated ________ _____________.

mass divergence

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Cyclogenesis occures when (divergence/convergence) aloft exceeds (divergence/convergence) at low levels, resulting in net mass (divergence/convergence) and surface pressure (falls/rises).

divergence
convergence
divergence
falls

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QG ascent results in (stretching/compression) and pressure (falls/rises).

stretching

falls

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Ignoring friction, and in regards to the QG omega equation, what 3 things can contribute to ascent, pressure falls, and cyclogenesis?
These effects are most pronouned when static stability is (high/low).

1) Vorticity advection becoming more cyclonic (or less anticyclonic) with height.
2) A local maximum in temperature advetion.
3) A local maximum in diabatic heating.
- low

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In regards to vorticity advection becoming more cyclonic with height as a contributor to cyclogenesis, we typically look for (CVA/AVA) at ______ mb.

CVA

500

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In regards to cyclogenesis and the contributions of a local maximum in temperature advection, we typically look for (warm/cold) advection, such as along a (warm/cold) front or occluded front.

warm

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In regards to cyclogenesis and static stability, this is exemplified by an upper-level trough inducing cyclogenesis more easily if the static stability is (low/high).

low

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Synoptic experience in cyclogenesis:

(CVA/AVA) downstream of an upper-level trough contributes to pressure (falls/rises) and cyclogenesis.

CVA

falls

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Synoptic experience in cyclogenesis:

(Warm/cold) advection along a (warm/cold) front contributes to pressure (falls/rises) and cyclogenesis.

warm
warm
falls

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Synoptic experience in cyclogenesis:

Diabatic heating contributes to pressure (falls/rises) and cyclogenesis.

falls

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Synoptic experience in cyclogenesis:
In frontal cyclone development, CVA, warm advection, and diabatic heating all contribute to a mutual ______________ of the surface cyclone and upper level wave.

amplification.

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Synoptic experience in cyclogenesis:

Stretching (downstream/upstream) of topography can contribute to cyclogenesis.

downstream

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In an idealized example of cyclogenesis, consider a 3-part conceptual model, and answer the following about PART 1:

500-mb (CVA/AVA) contributes to surface cyclogenesis
(Low/Upper)-level warm advection ahead of cyclone amplifies (downstream/upstream) ridge
(Low/Upper)-level cold advection ahead of cyclone amplified (low/upper)-level trough.

CVA
Low
downstream
Low
Upper

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In an idealized example of cyclogenesis, consider a 3-part conceptual model, and answer the following about PART 2:

Wavelength of upper-level wave (shortens/lengthens)
(CVA/AVA) intensifies
Surface development (continues/diminishes)
(Low/Upper)-level warm and cold advection intensify
Surface cyclone and upper-level (trough/ridge) mutually amplify
Diabatic (heating/cooling) along warm/occluded front further enhances surface development and (low/upper)-level wave amplification.

shortens
CVA
low
trough
heating
upper

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In an idealized example of cyclogenesis, consider a 3-part conceptual model, and answer the following about PART 3:

Cyclone becomes veritically (stacked/removed)
QG forcing for (ascent/descent) weakens
Development (ceases/revitalizes)

stacked
ascent
ceases

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Synoptic experience in anticyclogenesis: | AVA (upstream/downstream) of an upper-level ridge contributes to pressure (rises/falls) and anticyclogenesis

downstream | rises

``` Synoptic experience in anticyclogenesis: A local (maximum/minimum) in cold advection contributes to pressure rises and anticyclogenesis. ```

minimum

Synoptic experience in anticyclogenesis: | Diabatic (radiational) (heating/cooling) contributes to pressure rises and anticyclogenesis.

cooling

Synoptic experience in anticyclogenesis: | (Stretching/Compression) upstream of topography can contribute to anticyclogenesis.

Compression

From a PV perspective, cyclogenesis results from the coupling and mutual amplification of surface (cyclonic/temperature) and upper-level (cyclonic/temperature) PV anomalies, with contributions from diabatically generated PV (cyclonic/anticyclonic) anomalies.

temperature cyclonic cyclonic

From a PV perspective, a surface (warm/cold) anomaly acts like a cyclonic PV anomaly ad a surface (warm/cold) anomaly acts like an anticyclonic PV anomaly.

warm | cold

Cyclogensis from a PV perspective: Answer the questions to the first 2/5 steps of cyclongenesis. 1) Upper-level (cyclonic/anticyclonic) PV anomaly overtakes a (low/upper)-level frontal zone. 2) (Cyclonic/anticyclonic) circulation associated with upper-level PV anomaly induces a (warm/cold) tongue along the frontal zone.

cyclonic low cyclonic warm

Cyclogensis from a PV perspective: Answer the questions to the last 3/5 steps of cyclongenesis. 3) Warm tongue acts like a(n) (cyclonic/anticyclonic) PV anomaly, inducing a(n) (cyclonic/anticyclonic) circulation that extends upward and further amplifies the upper-level (cyclonic/anticyclonic) PV anomaly 4) The upper-level and surface thermal anomalies become phase locked and mutually (amplify/dampen), resulting in cyclogenesis. 5) (Adiabatically/Diabatically) generated PV can be a third building block in the process.

``` cyclonic cyclonic cyclonic amplify diabatically ```

What is the Norwegian Cyclone Model? 1) Conceptual model describing the ________ ______ and ________ of extratropical cyclones. 2) Developed after World War I by the _______ School of ____________. 3) Defined modern meteorological ___________. 4) It's still widely used today.

life cycle and dynamics Bergen school of meteorology analysis

Part 1 of the initial description of an ideal cyclone explains that "two airmasses (warm and cold) separated by a fairly distinct (surface/upper-level) boundary that runs through the center of the system."

surface

In regards to Part 2 of the initial description of an ideal cyclone, is the following statement TRUE or FALSE? "the surface boundary is imagined to continue through a greater part of the troposphere at a small angle to the horizon."

True

Part 3 of the initial description of an ideal cyclone explains that "(warm/cold) air in the (warm/cold) sector is conveyed by a SW or W current and (ascends/descends) the wedge of (warm/cold) air ahead of the (warm/cold) front, producing (warm/cold)-frontal precipitation."

``` warm warm ascends cold warm warm ```

Part 4 of the initial description of an ideal cyclone explains that "the intrusion of (warm/cold) air from behind the system into the (warm/cold) sector lifts the (warm/cold) airmass, producing (warm/cold)-frontal precipitation.

cold warm warm cold

What are the 4 phases of the Norwegian Cyclone Model?

Initial Phase Open Wave Phase Secluded/Occluded Phase Maturity/Death

In the initial phase of the Norwegian Cyclone Model, two oppositely directed currents of different ___________ are separated by a nearly straight boundary. This boundary begins to bulge toward the (cold/warm) air at the place where the cyclone will form.

temperatures | cold

In the open wave phase of the Norwegian Cyclone Model, - the amplitude of the warm wave (increases/decreases) - (warm/cold) air moves cyclonically around the low center - (Warm/Cold) sector narrows

increases Cold Warm

In the secluded phase of the Norwegian Cyclone Model, the (cold/warm) front overtakes the (cold/warm) front south of the low center. A piece of the (warm/cold) sector is cut off.

cold warm warm

In the occluded phase of the Norwegian Cyclone Model, the remaining part of the (warm/cold) sector is removed from the surface.

warm

In the maturity/death phase of the Norwegian Cyclone Model, the occluded front dissipates and the cyclone becomes (symmetric/asymmetric) vortex of (cold/warm) air.

symmetric | cold

In regards to the vertical evolution of the open wave phase, - two wedges of (cold/warm) air approach each other. - intermediate (cold/warm) sector air is lifted - Transforms (potential/kinetic) energy to (potential/kinetic) energy.

cold warm potential kinetic

In regards to the vertical evolution of the occluded phase, - once two wedges have met on the ground, the upper (warm/cold) sector is lifted until the (warm/cold) sector has (warmed/cooled) adiabatically to the temperature of its surroundings. - throughout this phase, the cyclone gains (potential/kinetic) energy

warm warm cooled kinetic

An essential condition for cyclone formation is coexistence of warm and cold air (adjacent/separate) to each other.

adjacent.

All cyclones which are not yet occluded have (increasing/decreasing) kinetic energy.

increasing

Soon after occlusion, the cyclone begins to (fill/empty).

fill

In later stages of cyclone formation, the cyclone becomes a (homogenous/heterogenous) vortex of (cold/warm) air that consumes the previously generated kinetic energy.

homogenous | cold

What are the two types of occlusion? | Which type is most common?

warm and cold | cold

A cold type occlusion forms if air behind the cold front is (colder/warmer) than air ahead of the warm front. This has characteristics of (cold/warm) front with (narrow/broad) precipitation zone.

colder cold narrow

A warm type occlusion forms if air behind the cold front is (warmer/colder) than air ahead of the warm front. This has characteristics of (cold/warm) front with (narrow/broad) precipitation zone.

warmer warm broad

In a secondary cold front, the cold air may contain a series of secondary cold fronts accompanied by only small contrasts in ___________ and ________.

temperature and wind

The appearance of a strong secondary cold front that is stronger than the primary cold front indicates a ______________ of the cylclone

reinforcement

In refining the Norwegian Cyclone Model, what three new features were identified?

1) upper-level cold front 2) bent-back occlusion 3) false warm sector

An upper-level cold front accompanies (warm/cold)-type occlusions.

warm

A bent-back occlusion extends into (polar/subtropical) airstream (in front of/behind) the low.

polar | behind

The false warm sector occurs between what two features?

between the bent-back occlusion and primary cold front.

What two life cycle refinements were made to the Norwegian Cyclone Model in regards to the stages?

1) antecedent stage | 2) nascent stage

The refined antecedent stage to the Norwegian Cyclone Model is similar to what famous paper's description?

Bjerknes and Solberg (1922)

In the refined Nascent stage of the Norwegian Cyclone Model, there is a newly formed wave with velocity nearly equal to that of the (warm/cold)-sector air near the (ground/mid-troposphere)

warm | ground

Refinements to the wave cyclone phase of the NCM include 1) further (development/reduction) of cyclone and frontal wave 2) frontolysis occurs along (warm/cold) front (near/away from) low center 3) phase (lag/syncing) of upper-level wave relative to surface wave

development cold near lag

Refinements to the occluded stage of the NCM include - (cold/warm) front climbs (cold/warm) front and forms upper-level (cold/warm) front - Pressure (ridge/trough) forms to rear of cyclone and rotates (cyclonically/anticyclonically) around the low center. - (True or False) Near low-center, a bent-back occlusion may coincide with trough

``` cold warm cold trough anticyclonically True ```

Refinements to the occluded stage of the NCM include - (More/less) removed from low center; it may become a non-frontal (trough/ridge) - Cyclone regeneration can occur if bent-back front is (longer/shorter) and (stronger/weaker) than normal and separates polar airmasses of differing temperature.

More trough longer stronger

In regards to modifications and extensions of the NCM and frontal structure/dynamics... depiction of the polar front as a discontinuity separating tropical and polar airmasses is an (underidealizaiton/overidealization).

overidealization

In regards to modifications and extensions of the NCM and frontal structure/dynamics... Upper-level and surface-based fronts may be (continuous/discontinuous) and have (differing/similar) dynamics.

discontinuous | differing

In regards to modifications and extensions of the NCM and frontal structure/dynamics... surface-based fronts may have (extreme/calm) intensity at the ground, but (weaken/strengthen) with height.

extreme | weaken

In regards to modifications and extensions of the NCM and frontal structure/dynamics... Frontal zones are better regarded as regions of (active/inactive) frontogenesis rather than (impermanent/semi-permanent/permanent) phenomenon.

active | semi-permanent

In regards to modifications and extensions of the NCM and frontal structure/dynamics... Fronts are often a (cause/consequence) of cyclogenesis rather than the (cause/consequence)

consequence | cause

In regards to modifications and extensions of the NCM and cyclone dynamics... Cyclone development may be viewed as a consequence of (baroclinic/frontal) instability rather than (barclinic/frontal) instabilities.

baroclinic | frontal

In regards to modifications and extensions of the NCM and cyclone dynamics... There are 3 major building blocks for observed cyclogenesis (thanks to the discovery of jet stream and development of PV thinking). Name these 3 major building blocks.

1) Upper-level trough/cyclonic PV anomaly 2) Surface front (surrogate cyclonic PV anomaly) 3) Diabatic Heating

In regards to modifications and extensions of the NCM and cyclone dynamics... There are patterns of cyclone development not envisioned by the Bergen School. Name an example.

Cyclogenesis in polar airstreams.

What is the definition of Lake Effect Snow, according to the Glossary of Meteorology?

Precipitation occurring near or downwind from the shore of a lake resulting from the warming (destabilization) and moistening of relatively cold air during passage over a warm body of water.

What are 5 additional factors to lake effect snow?

1) lake-lake interactions and aggregate effects (Great Lakes) 2) Boundary layer and thermally driven circulations 3) Orography 4) surface roughness contrasts 5) Ice cover

What are 5 morphological types of Lake Effect Snow?

1) Broad Coverage 2) Long-Lake-Axis-Parallel (LLAP) band 3) Hybrid 4) Shoreline Band 5) Mesoscale Vortices

What feature is responsible for the broad coverage type of Lake Effect Snow?

Horizontal Roll or Benard Convection

How are LLAP bands, which produce the heaviest snowfall, organized?

By land-breeze-induced convergence

Hybrid types of Lake Effect Snow have characteristics of what 2 morphological types? Hybrid types typically feature a connection to (upstream/downstream) lake(s).

broad coverage and LLAP | upstream

Shoreline bands of lake effect snow form along (land/lake) breeze during (weak/strong) flow. The exhibit (little/much) movement.

land weak little

Mesoscale vortices type of Lake Effect Snow typically form where the shore is "_______-______." This phenomenon is relatively rare.

bowl-shaped

The Tug Hill Plateau experiences what morphological type of lake effect snow? Some of the most intense snowstorms on Earth happen here,.

LLAP bands

In regards to the diurnal variability in the Tug Hill Plateau... - in fall and spring, lake-effect is (more/less common) overnight/early int he morning hours, and (more/less) common afternoon/evening. - (No/Strong) signal in winter - (Stronger/weaker) signal than over GSL

more less no weaker

For Lake Effect Snow on the GSL, match the percentages with how often the specific type of lake effect snow occurs. 1) Non-banded 2) Mixed Mode 3) Banded a) 25% b) 20% c) 55%

Non-banded - 55% Mixed Mode - 25% Banded - 20%

IN GSL Lake Effect Snow, do 1) rare and intense or 2) common and mild events dominate?

rare and intense

93% of GSL lake effect snow events occurs at lake-700-mb temperature gradients greater than or equal to what temperature (in dec C)?

16 deg C

For predicting Lake Effect Snow in the GSL, is it more appropriate to use a seasonally varying thresholed for lake-700-mb temperature gradients, or a fixed threshold?

varying threshold

Under marginal instabilities, environment conditions (moisture, wind direction) in the GSL are more frequently favored for lake-effect in (winter/fall and spring) than in (winter/fall and spring).

winter | fall and spring

True or False. | GSLE is not sensitive to moisture flux.

False.

What are 3 potential orographic effects to LES?

1) Precip enhancement 2) modificaition of the lake-effect system (initiation, intensity, morphology) 3) lake-effect systems can be altered by upstream and downstream topography

What is the hypothesis of LES in Japan in regards to the capping inversion?

Height of the CAP relative to mountain crest affects orographic ratio in lake-effect storms

Name 4 processes that influence lake-effect systems.

1) Upstream instability and moisture 2) Lake conditions (sfc temp, sub-sfc temp, salinity, ice cover) 3) Land breezes and PBL circulations 4) Orography

True or False. Orographic influences only include precipitation enhancement. If true, why doesn't it affect anything else? If false, what else does orography influence?

False. initiation, intensiyt, and morphology of lake-effect systems

This is too much to remember, and I"m lazy, but be familiar with the following 5 unresolved issues.

1) Morphological controls 2) Role of the CAP in modulating orographic enhancement 3) Possible role of boundary layer turbulence in precipitation enhancement 4) Understanding (and predicting) the spectrum of lake-driven and terrain-driven processes that influence lake-effect storms in areas of complex terrain. 5) Interdecadal variability & lake size

Final Exam Flashcards

(93 cards)