Chapter 18 Pt 2

Question 1

Where do frontal squall lines typically form?

Answer 1

South of a low pressure center. The frontal squall line is the comma tail part of an extratropical cyclone

Question 2

How do the winds change from the surface to aloft ahead of a frontal squall line - On East Side?

Answer 2

• SURFACE - SE to S (weak)

- ALOFT - SW (Stronger)

Question 3

How do the winds change from the surface to aloft ahead of a frontal squall line - On West Side?

Answer 3

• Surface - NW to W

- Aloft - W to SW (Stronger)

Question 4

What is the appearance of a frontal squall line on a radar reflectivity image?

Answer 4

Long line of thunderstorms (high reflectivity) with stratiform precipitation (low reflectivity) on either side (mostly behind it)

Question 5

From a satellite perspective, what part of a mid-latitude cyclone comma cloud does a frontal squall line form?

Answer 5

The Tail

Question 6

What is the lifetime of a frontal squall line?

Answer 6

Hours to days since the advancing front continually forces warm air to rise over it.

Question 7

What mechanism is responsible for lifting the conditionally unstable air to its level of free convection (LFC) in a frontal squall line?

Answer 7

Either a Cold front, an upper level front, or a dryline

Question 8

What causes the anvil of a squall line to form?

Answer 8

Since the tropopause acts as a lid on the t-storms, the cloud is forced to spread horizontally

Question 9

What can Supercell Thunderstorms cause?

Answer 9

• Tornadoes
• Strong Straight Line Winds
• Large Hail (Up to grapefruit size)

Question 10

How strong is the updraft in a supercell thunderstorm?

Answer 10

45 mph to greater that 100mph

Question 11

What 4 conditions are required for supercell thunderstorm to form?

Answer 11

• Conditionally unstable atmosphere
• Very humid low level air
• Moderate to strong vertical wind shear in conditionally unstable layer
• A trigger mechanism

Question 12

How can conditional instability develop in the atmosphere?

Answer 12

Either surface heating or by cold air advection aloft (Either increases environmental lapse rate)

Question 13

What does CAPE tell us about the updraft in a thunderstorm?

Answer 13

The maximum upward speed of the updraft

Question 14

What are the 8 features of a supercell thunderstorm?

Answer 14

• Tilted, rotating updraft (mesocyclone)
• Overshooting Top
• Anvil (Pushed to NE)
• Rear flanking line
• Bounded weak echo region
• Wall cloud
• Mammatus
• Virga

Question 15

Can tornadoes form from a mesocyclone?

Answer 15

Yes, often

Question 16

Is Mesocyclone just a fancy word for tornado?

Answer 16

No

Question 17

Overshooting Tops

Answer 17

The the clouds pop over the tropopause into the stratosphere

Question 18

Wall cloud

Answer 18

A lowered cloud base in the vicinity of the updraft that is often observed to be rotating. The wall cloud rotates as a result of the mesocyclone

Question 19

Virga

Answer 19

Rain/Snow/Ice that evaporates/Sublimates before reaching ground.

Question 20

Why is there a rain free base just below the updraft?

Answer 20

Small cloud droplets are first forming there in the updraft (, they flow up into tropospheric winds.

Question 21

Why will the largest hail (if present) will fall on perimeter of rain-free base?

Answer 21

This is because large hail cant make it far from updraft before quickly falling out of storm