Lesson 401 Cyclonic Development

Question 1

List the the three factors that affect the central value of a low pressure system.
TDD

Answer 1

Topography
Diurnal pressure changes
Diabatic influences

Question 2

List the six factors which contribute to divergence and convergence in devolving low pressure systems:
HHSSLH

Answer 2

Horizontal thermal advection 
Horizontal vorticity advection 
Surface vorticity 
Sensible heat transfer
Latent heat transfer
Heat transfer by vertical motion

Question 3

A baroclinic zone in the atmosphere is when there is a:

Answer 3

Horizontal temperature gradient on the isobaric surface.

Question 4

When an atmosphere is said to be baroclinic there can be changes in temperature, divergence, and convergence due to _________ ________ all resulting in ________ motion.

Answer 4

Thermal advection

Vertical

Question 5

The atmosphere is said to be barotropic when there is no …

Answer 5

Variation in its temperature along an isobaric surface (at a given pressure level)

Question 6

A barotropic atmosphere is thus characterized by the _________ of a temperature gradient on an isobaric surface.

Answer 6

Absence

Question 7

The ________ the thermal contrast, the _________ the baroclinic zone.

Answer 7

Larger

Stronger

Question 8

List the five stages in the life cycle of a baroclinic depression.
FDMOD

Answer 8

Formation
Development
Maturity 
Occlusion
Dissipation

Question 9

List the five methods that can be used to indicate the motion of a low pressure system.
HI5IB

Answer 9

History 
Isallobaric pattern
500 hPa flow
Isobaric pattern 
Baroclinic zone

Question 10

List the four thermodynamic factors favourable for the development of summer severe weather.
WCAD

Answer 10

Warming in the low levels
Cooling at upper levels
Adding moisture in the low levels
Drying at upper levels

Question 11

List the three dynamic factors favourable for the development of summer severe weather
LUV

Answer 11

Low level convergence
Upper divergence
Vertical wind shear

Question 12

List the characteristics of a tornado

Answer 12

Mesocyclone 
Very intense wind vortex
Small diameter
Extends from cumulonimbus 
Irregular track
Duration
Accompanied by other thunderstorm phenomena
*waterspout over water

Question 13

List the five stability indices commonly used in Canada

LSTGS

Answer 13

Lifted index (LI)
Showalter index (SI)
Total-totals index (TT)
George index (K)
Sly index

Question 14

Examples of severe winter weather for which weather warnings are issued are:

Answer 14

Blizzards,cold wave, heavy snowfall, freezing rain, strong wind, heavy blowing snow, freezing spray, wind chill, heavy rain, snow squalls.

Question 15

A blizzard is officially defined as a storm with:

Answer 15

Visibility less than 1 km in snow and/or blowing snow
Wind > 40 km/h
Temperature < -10 C
The above must persist for 6 hours or more.

Question 16

Heavy snow is defined as _____ cm or more accumulation in _____ hours (or less) from a particular system.

Answer 16

15

24

Question 17

What are the five characteristics associated with snow squalls
SNSDI

Answer 17

Shallow systems (tops generally less than 10,000')
Narrow band of precipitation 
Snowfall can be heavy
Duration - several hours to days
Inland penetration up to 200 km

Question 18

List the winter low pressure systems

Answer 18

Pacific lows, Alberta, Nebraska, Colorado, Great Lake lows, Atlantic lows, Newfoundland lows, Davis strait lows.

Question 19

Colorado lows experience ________ to _________ snowfalls. Lows which track further south often bring ________ ________.

Answer 19

Moderate to heavy

Freezing rain

Question 20

Snowfalls associated with Alberta lows rarely exceed _____ cm.

Answer 20

15

Question 21

Atlantic lows are often accompanied by _________ precipitation of all types. They produce _______ snowfalls in Labrador and Northern Quebec.

Answer 21

Abundant

Heavy

Question 22

List the three factors necessary for the formation of winter convective clouds (streamers):
LUL

Answer 22

Long fetch (150 km or more)
Unstable temperature profile (difference of 13 C or greater between lake temp. and 850 hPa level.)
Little wind shear (30 deg. or less below 3 km)

Question 23

To diagnose instability, look for:

PPI

Answer 23

Pools or troughs of cold air aloft (700 hPa chart)
Pools or ridges of warm air in low levels
Indications of lapse rates higher than saturated adiabatic lapse rates

Question 24

List the six stages of a baroclinic depression

Answer 24

Wave stage 
Developing comma
Mature comma
Occluding system
Occluded system
Dissipation