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Met 421 > Met 421 Exam 2 > Flashcards

Met 421 Exam 2 Flashcards

1
Q

Isentropes

A

-Line of constant potential temperature which is a line of constant entropy.

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2
Q

Advantages of Isentropic Analysis

A
  • Provides clear visual depiction of air parcel motion
  • Provides explicit representation of vertical motion on horizontal maps.
  • Adiabatic assumption is quite good
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3
Q

How does error introduced by diabatic processes effect omega?

A
  • Error introduced by diabatic processes does not change sign of omega; stronger but of same sign.
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4
Q

Isentropic analysis with cross-isobar wind

A
  • Wind blowing from high to low pressure: Rising motion (ascent)
  • From low to high pressure: Sinking motion (subsidence)
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5
Q

Isentropic Vertical Motion Equation Terms

A
  • Term A: Local Pressure tendency
  • Term B: Pressure advection.
  • Term C: Diabatic heating/cooling.
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6
Q

Frozen Wave Approximation

A

-Following the motion of the weather system, the value of S is constant.

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7
Q

Classifying cyclones based on Potential Vorticity: Extratropical Low Pressure System

A
  • Main cyclonic PV feature is of stratospheric origin, with some contribution from diabatic processes.
  • Fig 4.6 A
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8
Q

Classifying cyclones based on Potential Vorticity: Tropical Low Pressure System

A
  • Main PV feature is of diabatic origin.
  • Has a warm core structure
  • Absence of stratospheric influences
  • Fig 4.6 B
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9
Q

Classifying cyclones based on Potential Vorticity: Subtropical Low Pressure System

A
  • PV feature originates from both stratospheric and diabatic processes.
  • Fig 4.6 C
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10
Q

How is PV similar to potential temperature?

A

-PV represents the vorticity the air would have if it were adiabatically adjusted to a reference latitude.

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11
Q

What role do cyclones play in Earth’s system?

A
  • Precipitation
  • Drive downward Hadley branch
  • Equator to pole energy transport.
  • Latent heat transport
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12
Q

Cyclone formation: Upper waves

A

-Upper waves create patterns of divergence aloft.

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13
Q

Frontal zone and vorticity

A
  • Vorticity spins up twice as fast in tht frontal zone relative to locations outside of the zone.
  • Cyclones prefer to spin up in areas of large pre-existing vorticity such as fronts and inverted troughs.
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14
Q

What happens to the strength of the upper wave as trough deepens?

A

-Upper wave strengthens as trough deepens, ridge builds to the east.

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15
Q

WAA/CAA and heights aloft

A
  • Warm air advection -> Thickness increases -> Heights rise aloft
  • Cold air advection -> Thickness decreases -> Heights falls aloft
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16
Q

Sutcliffe-Petterssen Self Development

A
  • Upper wave pattern amplified due to thermal advection.
  • Shorter wavelength
  • Larger amplitude
  • Strong differential vorticity advection
  • Lower surface pressure
  • Strong winds
17
Q

Miller Type A vs Type B cyclogenesis

A
  • Type A: Low pressure center moves continuously NE along coast, NO REDEVELOPMENT.
  • Type B: Low pressure center REDEVELOPS along coast, primary dies inland/
18
Q

Cyclone classifications

A
  • Petterssen type A
  • Petterssen type B
  • Petterssen type C
  • Miller type A
  • Miller type B
19
Q

What method is the frozen wave approximation?

A

-LaGrangian method

20
Q

What is a front?

A

-There isnt much consensus as to what the exact definition is, but Fronts can be thought of as air mass boundaries. Or as hyoergradients of temperature.

21
Q

Across-front length scale

A

-100km

22
Q

Along-front length scale

A

-1000km

23
Q

Why do we expect fronts to often be accompanied by clouds and precipitation?

A
  • Areas of strong temp. gradient are often associated with disruption of thermal wind balance.
  • QG forcing
24
Q

9 Frontal Characteristics

A
  • Large horizontal contrast in temp. or moisture
  • Minimum in pressure and maximum in cyclonic vorticity
  • Strong wind shear (wind shift)
  • Large static stability
  • Ascending air which leads to clouds and precip
  • May trigger sever weather
  • Dictates precipitation type
  • Not always obvious from isotherm field
  • Usually most intense at surface and diminishes aloft
25
Q

Why do fronts matter?

A
  • Initiation of sever weather
  • Cloud and precipitation forecasts
  • Wind speed and direction
  • Temperature and humidity forecast
  • Precipitation types forecast
26
Q

How does shearing affect cold/warm fronts?

A
  • Shearing STRENGTHENS COLD front

- Shearing WEAKENS WARM front.

27
Q

Frontogenesis vs Frontlysis

A
  • Frontogenesis: warm air gets warmer and cold air gets colder.
  • Frontolysis: Opposite of frontogenesis.
28
Q

Deformation pattern and the axis of dilatation. FG or FL?

A
  • Axis of dilatation ORTHOGONAL to isotherms = FRONTOLYSIS.

- Axis of dilatation PARALLEL to isoherms = FRONTOGENESIS

29
Q

Axis of dilatation parallel to isotherms

A

FRONTOGENESIS

30
Q

Axis of dilatation orthogonal to isotherms

A

FRONTOLYSIS

31
Q

How does SHEARING change frontal intensity?

A

-Through differential temperature advection by FRONT PARALLEL component of flow

32
Q

How does CONFLUENCE change frontal intensity?

A

-Through differential temperature advection by FRONT NORMAL component of flow

33
Q

How does TILTING change frontal intensity?

A

-Through differential vertical motion.

34
Q

What processes does Differential Diabatic Heating include?

A
  • Radiation
  • Latent heat release/absorption
  • Surface fluxes
35
Q

Anafronts vs Katafronts location of precipitation

A
  • Katafront: Precipitation at or ahead of surface cold front.
  • Anafront: Precipitation at or behind surface front.
36
Q

Strong vs Moderate temperature gradients

A
  • Strong: 8 Degrees C/ 110 km

- Moderate: 8 Degrees C/ 220 km

37
Q

Definition of Frontogenesis

A

-Using potential temperature as our scalar field, the frontogenesis function is defined as the time rate of change of the horizontal potential temp gradient.

38
Q

4 Terms of the Frontogenesis Equation

A
  • Shearing
  • Confluence
  • Tilting
  • Diabatic
39
Q

How does vertical potential temp gradient relate to PV?

A

-Increase in vertical theta gradient = increase in PV.

Met 421 (3 decks)

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