chapter 4 Flashcards

1
Q

The QG Thermodynamic Equation

This equation can be derived from

A

the thermodynamic energy equation in pressure coordinates

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2
Q

the following is the

A

the thermodynamic energy equation in pressure coordinates

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3
Q

describe each term in the equation

A
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4
Q

cp and a in the following equation means

A
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5
Q

describe the following terms in the equation

A
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6
Q

this is called

A

static stability parameter

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7
Q
A

is a positive number for a stable atmosphere, and a negative number for an unstable atmosphere.

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8
Q

the following is the

A

the quasi geostrophic (QG) thermodynamic energy equation in pressure coordinates

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9
Q

in this equation the …………………. is simply substituted for ……………………………..

A

geostrophic wind is simply substituted for the actual wind in the advection term

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10
Q

the following terms are

A
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11
Q

the above equation states that

A

temperature change at a particular location and height is a function of temperature advection by geostrophic wind and vertical motion.

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12
Q

Warm temperature advection result in

A
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13
Q

cold temperature advection result in

A
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14
Q

Ascent vertical motion result in

A
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15
Q

Decent vertical motion result in

A
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16
Q

Diabatic effects:

A

Diurnal (day and night) l heating/cooling plays a major role in temperature changes near the surface

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17
Q

(5) is the

A

hydrostatic equation in height coordinates (x, y, z)

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18
Q

(6) is the

A

the hydrostatic equation in pressure coordinates

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19
Q

the geopotential tendency

A
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20
Q

the following is the

A

QG thermodynamic energy equation

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21
Q

Note that equation 5 and 7 are identical, which are written in different forms, because

A

in a hydrostatic atmosphere, do Φ⁄do p is proportional to the temperature (T) of the layer.

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22
Q

the following is the

A

QG vorticity equation

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23
Q

The geopotential tendency equation is derived from

A

The QG Thermodynamic Energy Eq.

QG Vorticity Eq.

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24
Q

For a sinusoidal disturbance having a zero mean value, the

A

horizontal Laplacian of a field is proportional to the negative of the field

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25
......................................................................, the horizontal Laplacian of a field is proportional to the negative of the field
For a sinusoidal disturbance having a zero mean value
26
geopotential tendency is positive
27
the following is the
absolute vorticity advection
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PVA =
29
NVA
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when heights are rising T-adv. increases with
pressure
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when heights are rising T-adv. decreases with
height
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when heights are falling T-adv. decreases with
pressure
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when heights are falling T-adv. increases with
height
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Strong CA over ................... has the same effect as .................. over ....................
weak CA weak WA strong WA
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It is the vertical derivative of the advection that matters. Strong CA over weak CA has the same effect as weak WA over strong WA, because in both cases the
derivative has the same value
36
The differential heating term (third term on RHS) behaves similarly to the
differential thermal advection term.
37
That is, the Term-C is proportional to
he vertical derivative of diabatic heating
38
**when heights rise:** heating cooling
Heating decreases with height Cooling increases with height
39
**when heights fall:** heating cooling
Heating increases with height Cooling decreases with height
40
Another useful way of writing the essence of the Q-G tendency equation is in qualitative form, as:
41
Thus, in quasi-geostrophic theory, there are only three ways for heights to
fall
42
Thus, in quasi-geostrophic theory, there are only three ways for **heights to fall**. These are through:
1. Positive Vorticity Advection 2. WA that increases with height 3. Diabatic heating that increases with height
43
Le Chatelier’s Principle, states that
many natural systems will resist changes, and if forced to change, will react with process that try to restore the original state.
44
We can see Le Chatelier’s principle at work in
the differential thermal advection and diabatic heating terms of the Q-G tendency equation
45
For example, cold advection (or .........................) over warm advection (or ...............................) forces
diabatic cooling diabatic heating height rises at 500 mb, as well as height falls at 200 and 1000 mb
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A
200 mb
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B
500 mb
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C
1000 mb
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D
cold advection
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E
Warm avection
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A
200 mb
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B
500 mb
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C
1000 mb
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D
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E
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these height rises and falls indicate that there must be a change in
the vorticity at these levels
57
However, these height rises and falls indicate that there must be a change in the vorticity at these levels:
* increased vorticity where there are height falls, and * decreased vorticity where there are height rises
58
To accomplish this vorticity change in a .......................... framework
quasi-geostrophic
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To accomplish this vorticity change in a quasi-geostrophic framework, there must be
convergence where there are height falls, and divergence where there are height rises.
60
The convergence/divergence pattern leads to:
* upward motion and adiabatic cooling in the lower levels, and * subsidence and adiabatic warming in the upper levels.
61
The adiabatic heating/cooling thus, opposes the
original temperature change due to advection.
62
Le Chatelier’s Principle doesn’t mean that
the effects of the differential heating (advection) will be completely cancelled by the adiabatic heating/cooling from the secondary circulation, but does illustrate that the atmosphere will resist the changes imposed by the thermal forcing, and will respond with a secondary circulation.