Q vector

Question 1

What will QG Theory do for us?
–It reveals how …………………………………….. and ………………………………… constrain and simplify atmospheric motions, but in a realistic manner

Answer 1

hydrostatic balance and geostrophic balance

Question 2

What will QG Theory do for us?

It provides a simple framework within which we can understand and diagnose the ……………………………………

Answer 2

evolution of three-dimensional synoptic-scale weather systems

Question 3

What will QG Theory do for us?

It predicts the evolution of synoptic-scale systems by

Answer 3

diagnosing changes in the local geopotential height field from the observed distributions of vorticity advection and temperature advection.

Question 4

What will QG Theory do for us?

It estimates synoptic-scale ………………………………………………………….

Answer 4

vertical motions from the observed distribution of vorticity and temperature advection.

Question 5

What will QG Theory do for us?

It helps us to understand how the ………………………………………………….and the ………………………………………………………………….interact to create ………………………………..that result in realistic synoptic scale weather patterns

Answer 5

mass fields (via horizontal temperature advection)

momentum fields (via horizontal vorticity advection)

vertical circulations

Question 6

What will QG Theory do for us?

It offers physical insight into the forcing of ………………………………………………. and ……………………………………………………….associated with mid-latitude cyclones

Answer 6

vertical motion and the cloud/precipitation patterns

Question 7

Rotational momentum:

Answer 7

Rotation around an axis (less effort)

Question 8

Momentum equations and linear momentum

Answer 8

momentum equations: du/dt, dv/dt. dw/dt

linear momentum: ΣF = dp/dt = m* d/dt = ma

Question 9

From our mathematical derivation of QG theory, QG theory has the following assumptions

Answer 9

• Geostrophic balance (i.e. we neglect all local changes in the ageostrophic wind) >> No difference between geostrophic & wind (actual)
• Hydrostatic balance >> No vertical motion (parcel of air at rest)
• Horizontal advection by the geostrophic winds only (i.e. we neglect the advection of the ageostrophic momentum by the geostrophic wind and the vertical advection of momentum)
• No friction or orographic effects
• No diabatic heating / cooling
• No spatial or temporal changes in static stability >> consider midlatitude weather is stable

Question 10

meaning of adiabatic

Answer 10

No change of heat between air parcel and surrounding air “when air parcel is rising it will cool due to expansion/increase of volume”

(Source of heat must exist)

Question 11

QG Height Tendency Equation

Answer 11

Question 12

The following equation represents

Answer 12

QG height tendency equation

Question 13

Term A corresponds to

Answer 13

local horizontal advection of geostrophic vorticity

Question 14

Term B correspond to

Answer 14

change in temperature advection with height

Question 15

QG omega equation

Answer 15

Question 16

The following equation represents

Answer 16

QG omega equation

Question 17

Term A correspond to

Answer 17

change in vorticity advection with height

Question 18

Term B correspond to

Answer 18

local maximum in temperature advection

Question 19

If large changes in the vorticity advection with height are observed, then you should expect…………………………………….

Answer 19

large vertical motions

Question 20

The stronger the temperature advection, the stronger the ……………………….

Answer 20

vertical motion

Question 21

If WAA is observed at several consecutive pressure levels, expect a…………………………………………………motion

Answer 21

deep layer of rising

Question 22

The QG omega equation is proportional to

Answer 22

vorticity advection & advection of maximum temperature (local)

Question 23

vorticity advection & advection of maximum temperature (local) usually work

Answer 23

opposite to each other

Question 24

if term A in the QG omega equation is +ve and term B is -ve the result is

Answer 24

rising air

Question 25

you can find which is dominant cold advection or cyclonic by

Answer 25

Q vectors because they are working against each other

“rate of change of potential temperature in geostrophic balance”

Question 26

If term A and B are working together

Answer 26

PVA and WAA are on top of each other

Question 27

The Q-vector is defined as

Answer 27

the change of the potential temperature gradient vector of a parcel following the geostrophic motion.

Question 28

Q-vector equation

Answer 28

Question 29

the following equation is for

Answer 29

Q-vectors

Question 30

What does each term in the Q-vector equation mean?

Answer 30

d_g /dt : rate of change of potential temperature gradient in geostrophic motion

gradient of potential temperature

0: potential temperature

Question 31

for the equation both terms on the LHS are the

Answer 31

both terms are the second derivative of omega

the first term is horizontally the second term is vertically (the divergence of Q)

Question 32

in the equation w is

Answer 32

w is proportional to -2 grad Q

w depends on divergence and convergence of Q

Question 33

when Q is positive and when its negative……

Answer 33

+ve > sinking air > divergence

-ve> rising air > convergence

Question 34

when grad Q is positive

Answer 34

Divergence on the ground

Question 35

the purpose of Q-vectors

Answer 35

to solve conflict between omega equation

Question 36

Q vectors are useful for the following reason

Answer 36

Eliminates competition between terms in the QG 𝜔 equation

Question 37

The weaknesses of Q-vectors are as follows

Answer 37

It contains all of the limiting assumptions of QG theory (i.e. neglect of diabatic heating/cooling, variations in static stability, etc.)

Question 38

𝑄 is typically evaluated within ………………………..because this brackets the level of non-divergence ………………………..

Answer 38

400-700 mb

(~550 mb )

Question 39

in the upper trough the gradient is from

Answer 39

high to low

Question 40

in the upper ridge …..

Answer 40

warming in the upper air > stable air > ridge

Question 41

A and B are areas of

Answer 41

A: cooling

B: Warming