Deck 12: Middle-Latitude Cyclones

Question 1

Which below is not a name given to a large cyclonic storm system that forms in the middle latitudes?

A) middle latitude cyclone
B) extratropical cyclone
C) wave cyclone
D) anticyclone

Answer 1

D

Question 2

Cyclogenesis often occurs in regions without horizontal temperature gradients.

Answer 2

True

Question 3

Which of the scientists below was not one of the meteorologists who helped develop the polar front theory of a developing wave cyclone?

A) B.Bjerknes
B) C.G.Rossby
C) T.Bergeron
D) H.Solberg
E) J.Bjerknes

Answer 3

B

Question 4

For cyclogenesis to occur along a frontal wave,the winds aloft directly above the wave should be

A) diverging.
B) converging.
C) blowing straight from west to east.
D) increasing in speed uniformly over a broad area.

Question 5

Another term for explosive cyclogenesis used by meteorologists is

A) lee-side low development.
B) cut-off low cyclogenesis.
C) deepening shortwave.
D) baroclinic development.
E) bomb.

Question 6

If the flow of air into a surface low pressure area is greater than the divergence of air aloft,the surface pressure in the center of the low will

A) increase.
B) decrease.
C) remain the same.
D) deepen.

Question 7

A building anticyclone means

A) the central pressure is increasing.
B) the anticyclone is moving toward the east coast.
C) separate anticyclones are merging.
D) the anticyclone is causing a middle latitude storm to form.

Question 8

The polar front theory of a developing wave cyclone was conceived in

A) Norway.
B) Great Britain.
C) the United States.
D) Germany.
E) the Soviet Union.

Question 9

Which of the following is not associated with rising air motions?

A) overrunning
B) convergence of air at the surface
C) convergence of air aloft
D) divergence of air aloft

Question 10

A lee-side low forms

A) over the central Pacific Ocean.
B) near the equator.
C) on the upwind side of a mountain.
D) on the downwind side of a mountain.

Question 11

Which region is not considered to be a region where cyclogenesis often occurs?

A) eastern slopes of the Rocky Mountains
B) Atlantic Ocean near Cape Hatteras,North Carolina
C) California
D) Great Basin of the United States
E) Gulf of Mexico

Question 12

Northeasters (or nor'easters)are midlatitude storms commonly found

A) along the Pacific coast of North America.
B) along the Atlantic coast of North America.
C) along the Gulf coast of North America.
D) along both the Pacific and Atlantic coasts of North America.

Question 13

The development or strengthening of a middle latitude storm system is called

A) convergence.
B) divergence.
C) cyclogenesis.
D) frontolysis.

Question 14

According to the model of the life cycle of a wave cyclone,the storm system is normally most intense

A) as a frontal wave.
B) as a stable wave.
C) as an open wave.
D) as a stationary wave.
E) when the system first becomes occluded.

Question 15

Cyclogenesis is the ____ of a mid-latitude cyclone.

A) development or strengthening
B) weakening or dissipation
C) term for the exact midpoint
D) none of the above

Question 16

In the polar front theory of a developing wave cyclone,energy for the storm is usually derived from all but one of the following:

A) rising of warm air and the sinking of cold air
B) latent heat of condensation
C) an increase in surface winds
D) heat energy stored in the ground

Question 17

As westerly winds blow over a north-south oriented mountain range,the airflow is deflected in such a way that a trough forms on the ____________ side of the mountain.

A) upwind
B) downwind
C) both upwind and downwind
D) none of the above

Question 18

On a surface weather map that shows an open wave cyclone,the warm sector can be observed

A) ahead of an advancing cold front.
B) behind an advancing cold front.
C) ahead of an advancing cold-occluded front.
D) behind an advancing cold-occluded front.
E) ahead of an advancing warm front.

Question 19

The piling up of air above a region is called

A) thickening.
B) divergence.
C) cyclogenesis.
D) convergence.

Question 20

In the Southern Hemisphere,convergence and divergence don't play a role in the development of middle latitude cyclones.

Question 21

Jet streaks often occur away from jet streams.

Question 22

Rossby waves are also known as

A) stable waves.
B) shortwaves.
C) tidal waves.
D) longwaves.

Question 23

The warm sector is located

A) ahead of the warm front and behind the cold front.
B) ahead of the cold front and behind the warm front.
C) below the occluded front and above the cold front.

Question 24

Like hurricanes,polar lows have a clear area in their center.

Question 25

If the outflow of air around a surface high pressure area is greater than the convergence of air aloft,you would observe

A) in increase in pressure in the center of the high.
B) movement of the high toward the northeast.
C) a decrease in the central pressure.
D) strengthening in the high.

Question 26

For a surface storm system to intensify,the upper-level low (or trough)should be located to the ____ of the surface low.

A) north
B) south
C) east
D) west

Question 27

When upper-level divergence of air above a surface low pressure area is stronger than the convergence of surface air,the surface pressure will ____ and the storm itself will ____.

A) increase,intensify
B) increase,dissipate
C) decrease,intensify
D) decrease,dissipate

Question 28

A surface low pressure area with a deep upper-level trough to the west will tend to move toward the

A) northwest.
B) northeast.
C) southwest.
D) southeast.

Question 29

An upper-level trough that shows retrograde motion would probably be moving toward the

A) west.
B) east.
C) north.
D) south.

Question 30

When a deep upper-level trough is located to the east of a surface anticyclone,the surface anticyclone will tend to move toward the

A) northwest.
B) northeast.
C) southwest.
D) southeast.

Question 31

On an upper-level chart where the isotherms cross the isobars (or contours)and temperature advection occurs,the atmosphere is called

A) barotropic.
B) geostrophic.
C) hydrostatic.
D) baroclinic.

Question 32

Longwaves in the middle and upper troposphere usually have lengths on the order of

A) tens of kilometers.
B) hundreds of kilometers.
C) thousands of kilometers.
D) millions of kilometers.

Question 33

Atmospheric shortwaves usually move ____ than longwaves,and ____ when they move through a longwave ridge.

A) faster,weaken
B) faster,strengthen
C) slower,weaken
D) slower,strengthen

Question 34

Developing low pressure areas generally have ____ air near the surface and ____ air aloft.

A) converging,diverging
B) diverging,converging
C) converging,converging
D) diverging,diverging

Question 35

An upper-level pool of cold air that has broken away from the main flow is called

A) a cut-off low.
B) a shortwave.
C) a wave cyclone.
D) a lee-side low.

Question 36

Strong storms that develop over water,poleward of the polar front,are called

A) nor'easters.
B) upslope lows.
C) lee-side lows.
D) polar lows.
E) none of the above

Question 37

Atmospheric shortwaves usually move ____ at a speed that is ____ than longwaves.

A) east to west,faster
B) west to east,faster
C) east to west,slower
D) west to east,slower

Question 38

A small,moving disturbance imbedded in a longwave is called

A) a lee-side low.
B) a wave cyclone.
C) a shortwave.
D) a frontal wave.

Question 39

When an upper-level low lies directly above a surface low,

A) the surface low will probably weaken.
B) thunderstorms will develop.
C) a wave cyclone will begin to form.
D) the pressure of the surface low will decrease.
E) cyclogenesis will occur.

Question 40

The entrance region occurs ____________ of a jet streak,while the exit region occurs _________ of the jet streak.

A) downwind,upwind
B) upwind,downwind
C) ahead,above
D) downwind,above

Question 41

With the aid of a diagram,show why an intensifying surface low pressure center which is located just east of a deep upper-level trough will often move in a northeasterly direction.

Question 42

How do shortwaves differ from a longwaves in the development of middle latitude storms?

Question 43

Draw a sketch of a 500 mb chart that clearly shows a trough and a ridge.Where would you expect to find the maximum and minimum values of absolute vorticity? Where would you expect to find converging and diverging wind motions?

Question 44

The planetary vorticity of an air parcel moving from low toward high latitude in the Northern Hemisphere will

A) increase.
B) decrease.
C) remain constant.
D) change from positive to negative.

Question 45

Which of the following is true about vorticity?

A) Vorticity can be observed by satellites,even during cloudy conditions.
B) Planetary vorticity is always present.
C) Relative vorticity can be either positive or negative.
D) all of the above
E) none of the above

Question 46

Vorticity is always present in the atmosphere,even during fair weather.

Question 47

Temperature advection does not occur when the winds do not cross the isotherms.

Question 48

How can shortwaves be identified and followed on 500 mb charts?

Question 49

Lee-side lows are

A) storms (extratropical cyclones)that form on the eastern (lee)side of a mountain range.
B) thermal lows that form due to surface heating over deserts.
C) storms (tropical cyclones)that form near the Leeward Islands.
D) low pressure areas that form over oceans,then move onshore of the lee side of the coastline.

Question 50

Why does middle latitude storm development occur beneath troughs rather than ridges on a 500 mb chart?

Question 51

The type of weather system known as a "mid-latitude cyclone" cannot form over the tropical ocean because:

A) surface temperature contrasts are not large.
B) the ocean surface has a lot of waves.
C) the Coriolis force is weak in the tropics.
D) both surface temperature contrasts are not large and the ocean surface has a lot of waves.
E) both surface temperature contrasts are not large and the Coriolis force is weak in the tropics.

Question 52

Explain how cyclogenesis works.

Question 53

During baroclinic instability,

A) wave cyclones can intensify into large storm systems.
B) strong wind speed shear exists from the surface up to at least the 500 mb level.
C) rising and descending air motions exist.
D) temperature advection is occurring.
E) all of these

Question 54

List two regions in the United States where cyclogenesis is common.Why does cyclogenesis preferentially occur in these areas?

Question 55

Describe,in words or with a sketch,a wind flow pattern that will result in upper-level divergence.

Question 56

Why is it important locate and follow the movements of atmospheric shortwaves?

Question 57

Vorticity refers to

A) the rising and sinking of air along weather fronts.
B) the formation of clouds.
C) the spin of air parcels.
D) the changing of the seasons.
E) the development of a wave cyclone.

Question 58

If we assume that the absolute vorticity of flowing air is conserved,air moving northeastward will bend ____ to compensate for the ____ in the earth's vorticity.

A) anticyclonically,decrease
B) anticyclonically,increase
C) cyclonically,increase
D) cyclonically,decrease

Question 59

Describe or illustrate the various phases in the life cycle of a middle latitude storm according to the polar front theory.

Question 60

Which of the following statements is not correct about vorticity?

A) The earth's vorticity in the Northern Hemisphere is positive.
B) The earth's vorticity is zero at the poles.
C) Air that spins cyclonically possesses positive vorticity.
D) Absolute vorticity is the sum of the earth's vorticity and the relative vorticity.

Question 61

Suppose you observe a middle-latitude cyclone on the surface weather chart.What kind(s)of weather chart(s)would you want to examine to determine whether the cyclone is likely to strengthen or decay over the next 24 hours? What information would you hope to gain from each chart type?

Question 62

List some of the reasons why the polar front theory doesn't apply to storms in the tropics.

Question 63

Describe some of the ways in which the upper-level wind flow pattern can influence the development and movement of a middle latitude storm system.

Question 64

Describe how horizontal changes in both wind direction and wind speed can cause convergence and divergence.

Question 65

When making a weather forecast,which kind of chart is more important: a surface chart or a 500 mb chart?