QG theory Flashcards

1
Q

governing equations describe

A

the behavior of the atmosphere

2
Q

cons if governing equations

A

they are complex and thus it’s difficult to conceptualize the dynamical essence of synoptic-scale weather systems using the full set of equations.

3
Q

How was the governing equations simplified?

A
• by utilizing the observation that the flow in synoptic-scale weather systems is approximately geostrophic.
• By using a carefully designed set of assumptions
4
Q

Define the quasigeostrophic theory

A

simplified the governing equations of motion and combined them in ways that retain the fundamental dynamics of weather systems and yet are simple enough to comprehend.

5
Q

The QG framework simplifies the equation of motions into a set of diagnostic equations

A
• QG omega equation
• QG geopotential tendency
6
Q

geostrophic balance represents the

A

fundamental balance condition for mid-latitude synoptic-scale flow

7
Q

The geostrophic wind approximation is only strictly valid in

A

regions of zero wind acceleration

8
Q

There are two broad categories of flow in the atmosphere that will violate geostrophic balances

A
• Wind speed changes along the flow (i.e. jet streaks, regions of speed convergence/divergence)
• Wind direction changes along the flow (i.e. troughs and ridges, regions of confluence/diffluence)
9
Q

Define ageostrophic wind

A

The degree of departure from geostrophic balance that characterizes synoptic-scale motions can be assessed by considering the difference between the actual wind at a location and the calculate geostrophic wind at the same point.

10
Q

Ageostrophic wind is defined mathematically as

A
11
Q

………………………, this implies that the geostrophic wind is non-divergent.

A

Because all divergence/convergence necessarily implies an acceleration of the wind field,

12
Q

ALL…………………… in the synoptic-scale………………………………. is due to the presence of ageostrophic motion.

A

divergence , wind field

13
Q

ALL divergence in the synoptic-scale wind field is due to the

A

presence of ageostrophic motion.

14
Q

all vertical motion is due to the presence of

A

ageostrophic motion.

15
Q

ageostrophic wind is entirely responsible for

A
• the distribution of cyclones,
• anticyclones,
• clouds,
• and precipitation in the atmosphere.
16
Q

Despite the fact that the mid-latitude atmosphere is predominately in geostrophic balance, all of the important weather with which we are confronted develops as a direct result of the ……………………………….

A

often relatively small ageostrophic portion of the wind.

17
Q

To derive the relationship between ageostrophic wind and vertical motion, we first will write the

A

continuity equation in isobaric coordinates.

18
Q

if the geostrophic wind is nondivergent, we have

A
19
Q

the equation is for

A

relationship between ageostrophic wind and vertical motion

20
Q

the equation means

A

divergece of ageostrophic wind in upper air causes upward motion

21
Q

Equation for ageostrophic wind and horizontal acceleration:

A
22
Q
A

Equation for ageostrophic wind and horizontal acceleration

23
Q

Explain the following equation

A

Vag = Acceleration term in momentum equation and​ 1/f

24
Q

Based on the equation we conclude three properties

A
• The ageostrophic wind is a measure of the horizontal acceleration in the atmosphere
• The ageostrophic wind is perpendicular to the horizontal acceleration vector
• The ageostrophic wind is directed to the left of the acceleration vector in the Northern Hemisphere.
25
Q

The ageostrophic winds converge on ……………………….of the upper trough (on its ………………side)

A

the western side, upstream

26
Q

The ageostrophic winds converge on the western side of the upper trough (on its upstream side), leading to ………………..

A

downward vertical motion.

27
Q

The ageostrophic winds divergence on the …………………side of the upper trough (on its …………………………side),

A

eastern , downstream

28
Q

The ageostrophic winds divergence on the eastern side of the upper trough (on its downstream side), leading to …………………..vertical motion.

A

upward

29
Q

……………………………………. explains why there tends to be cloudy/stormy weather downstream of an upper level trough

A

divergence on the eastern side of the upper trough (on its downstream side), leading to upward vertical motion.

30
Q
A

Centripital acceleration

31
Q
A

ageostrophic wind