Thunderstorms

Question 1

Define Thunderstorm

Answer 1

Any type of weather being accompanied by the presence of thunder and lightning, originating from a cumulonimbus cloud

Question 2

List the 3 stages of evolution of a thunderstorm

Answer 2

Cumulus
Mature
Dissipation

Question 3

Describe the Cumulus stage with reference to:
Air motion
Size and duration
Temperature structure
Precipitation
turbulence
Icing

Answer 3

Air motion: all updrafts
Size and duration: 2-4 km grows till 11. tops to 30000ft. 10 -15 minutes
Temperature structure:temperature in the parcel is higher than environment due condensation.
Precipitation: none at surface
turbulence: MDT to SEV
Icing:MDT MXD within cloud around freezing lvl

Question 4

Describe the mature stage with reference to:
Air motion
Size and duration
Temperature structure
Precipitation
turbulence
Icing

Answer 4

Air motion:downdrafts due to falling precip, updrafts increase in speed and altitude. divergent at surface, gust front. PRESFR
Size and duration: avg 40000ft, low as 30000 ft high as 60000ft. 30 mins
Temperature structure:downdrafts colder than outside cld. updrafts warmer than outside cld.
Precipitation:Hail, start of precip is indicator of the beginning of the mature stage
turbulence:SEV in up/down drafts, microbursts
Icing: SEV MXD or CLR in cloud

Question 5

Describe the dissipation stage with reference to:
Air motion
Size and duration
Temperature structure
Precipitation
turbulence
Icing

Answer 5

Air motion: all downdrafts PRESRR
Size and duration:tops lower and breaks into CI, ACC, TCU and SC. 30 mins
Temperature structure: Downdrafts colder than outside air
Precipitation:light and ceases. Hail ends at the start of this stage
turbulence:OCNL SEV, less
Icing: LGT to MDT RIME or MXD

Question 6

List the 4 conditions essential for the formation of a thunderstorm

Answer 6

Moisture
Lift
Nuclei
Instability

Question 7

What is a good indicator of instability in the middle levels?

Answer 7

ACC in the morning

Question 8

List the 3 types of thunderstorms

Answer 8

Single cell
Multi-cell
Supercell

Question 9

In mid latitudes, isolated single cell storms caused by daytime heating are called:

Answer 9

Air mass thunderstorms

Question 10

Describe a single cell thunderstorm referencing:
Configuration:
Duration:
Severity of weather:

Answer 10

Configuration: 3 stages
Duration: 60-90 minutes
Severity of weather:rarely produces destructive winds/hail

Question 11

An organized cluster of CB’s that have dimensions of 100km or more are called

Answer 11

Mesoscale convective systems

Question 12

More circular mesoscale convective systems are called:

Answer 12

Mesoscale convective complexes

Question 13

Describe a multi-cell thunderstorm referencing:
Configuration:
Duration:
Severity of weather:

Answer 13

Configuration: Up/downdrafts, many individual cells, squall lines, MCS MCC
Duration: Can persist for more than 6 hours
Severity of weather:Strong winds, Hail, Heavy rain, Occasional tornadoes

Question 14

What is the most important characteristic of a supercell thunderstorm?

Answer 14

Its internal direction windshear allows updrafts and downdrafts to coexist for 30 mins or more

Question 15

Which type of thunderstorm can reach into the stratosphere?

Answer 15

Supercell

Question 16

Describe a Supercell thunderstorm referencing:
Configuration:
Duration:
Severity of weather:

Answer 16

Configuration: Cap head appearance
vertical shear allows up and downdrafts to occur
Duration: can persist for several hours, prolonged mature stage
Severity of weather:Heavy rain, large hail, tornadoes, strong outflow winds

Question 17

Vertical stretching (in a strong updraft) will cause:

Answer 17

increased rotation