QG theory

Question 1

governing equations describe

Answer 1

the behavior of the atmosphere

Question 2

cons if governing equations

Answer 2

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

Question 3

How was the governing equations simplified?

Answer 3

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

Question 4

Define the quasigeostrophic theory

Answer 4

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.

Question 5

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

Answer 5

• QG omega equation
• QG geopotential tendency

Question 6

geostrophic balance represents the

Answer 6

fundamental balance condition for mid-latitude synoptic-scale flow

Question 7

The geostrophic wind approximation is only strictly valid in

Answer 7

regions of zero wind acceleration

Question 8

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

Answer 8

• 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)

Question 9

Define ageostrophic wind

Answer 9

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.

Question 10

Ageostrophic wind is defined mathematically as

Answer 10

Question 11

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

Answer 11

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

Question 12

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

Answer 12

divergence , wind field

Question 13

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

Answer 13

presence of ageostrophic motion.

Question 14

all vertical motion is due to the presence of

Answer 14

ageostrophic motion.

Question 15

ageostrophic wind is entirely responsible for

Answer 15

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

Question 16

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 ……………………………….

Answer 16

often relatively small ageostrophic portion of the wind.

Question 17

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

Answer 17

continuity equation in isobaric coordinates.

Question 18

if the geostrophic wind is nondivergent, we have

Answer 18

Question 19

the equation is for

Answer 19

relationship between ageostrophic wind and vertical motion

Question 20

the equation means

Answer 20

divergece of ageostrophic wind in upper air causes upward motion

Question 21

Equation for ageostrophic wind and horizontal acceleration:

Answer 21

Question 22

Answer 22

Equation for ageostrophic wind and horizontal acceleration

Question 23

Explain the following equation

Answer 23

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

Question 24

Based on the equation we conclude three properties

Answer 24

• 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.

Question 25

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

Answer 25

the western side, upstream

Question 26

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

Answer 26

downward vertical motion.

Question 27

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

Answer 27

eastern , downstream

Question 28

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

Answer 28

upward

Question 29

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

Answer 29

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

Question 30

Answer 30

Centripital acceleration

Question 31

Answer 31

ageostrophic wind