Thunderstorms and Radar

Question 1

Other than the power control, the most important control on an airborne radar is the:

Answer 1

tilt control

Question 2

Airborne weather radar typically has what wavelength? Ground Based Radar has what wavelength?

Answer 2

3 cm and 5cm respectively

Question 3

The longer the wavelength of radar utilized, the larger:

Answer 3

the diameter of the antenna used

Question 4

If you wanted to be able to “see” cloud droplets (not preceipitation) on an airborne radar, would a smaller or larger wavelegth work better?

Answer 4

smaller (around .5cm)

Question 5

The intensity of the radar signal returned froma weather “target” is a function of what?

Answer 5

1. droplet size
2. droplet number density
3. composition of the hydrometeors

Question 6

With respect to radar beam width, greater accuracy occurs (at fixed wavelength) with a narrow beam, wide beam, or medium beam?

Answer 6

narrow beam

Question 7

Range resolution refers to the ability of radar to what?

Answer 7

distinguish between two targets the same direction from the radar, but at different distances

Question 8

In order to show as two separate targets, echoes must be separated by at least how many beam widths?

Answer 8

1 beam width

Question 9

Attenuation is any process that what?

Answer 9

reduces the power density of a radar beam

Question 10

Precipitation attenuation is worst for which band of radar?

Answer 10

x-band radar

Question 11

Range attenuatation is normally proportional to what”

Answer 11

the inverse of the square of the distance to the target

Question 12

a radar shadow occurs when what happens?

Answer 12

rain attenuates the signal so strongly that insufficient energy is returned to the radar receiver to be displayed

Question 13

The fundamental difference between the echo image of a non-severe storm and that of a severe storm is that the sever storm will exhibit what?

Answer 13

scalloped contour outlines

Question 14

You should avoid thunderstorms by what distance, when flying above the freezing level?

Answer 14

20 nm

Question 15

You should avoid thunderstorms by what distance, when flying below the freezing level?

Answer 15

10 nm

Question 16

The danger of flying into a radar shadow (on airborne radar) is what?

Answer 16

there may be undetected thunderstorm activity in the area of the radar shadow

Question 17

A hook echo on a radar scope is the signature of what?

Answer 17

a mesocyclone

Question 18

If a thunderstorm possesses a hook echo, in what quadrant of the storm would you expect to find it?

Answer 18

southwest

Question 19

Do all tornadic thunderstorms exhibit a well-defined hook echo?

Answer 19

no

Question 20

doppler radar measures what exactly?

Answer 20

1. radial velocity relative to the radar antenna
2. velocity shears
3. areas of likely turbulence

Question 21

What is a BWER?

Answer 21

bounded weak echo region, which is an area of low reflectivity radar returns, surrounded by high reflictivity returns, signifying an area of strong updrafts

Question 22

What does TVS stand for?

Answer 22

tornado vortex signature

Question 23

Stormscope and strikefinder detect what”

Answer 23

lightning discharges

Question 24

What are some strengths of spheric detectors, compared to airborne radar (lightning detectors)

Answer 24

lower cost, easier to use, little or no precipitation attenuation, and it can be used safely on the ground

Question 25

What are some weaknesses of spheric detectors compared to radar?

Answer 25

they are less precise than un-attenuated radar, can't show precip not associated with a thunderstorm, they experience aliasing of pixels toward the aircraft position, particularly when severe thunderstorms are present

Question 26

Most damage due to sever thudnerstorms is concentrated in which region of the US?

Answer 26

Central plains and east of mississippi river

Question 27

What are the national weather service criteria for a severe thunderstorm?

Answer 27

1. hail with diameter 1 in or greater, or 2. wind damage or wind gusts greater than 58 mph, or 3. a tornado

Question 28

What is necessary for the formation of a thunderstorm?

Answer 28

1. source of moisture 2. conditionally unstable atmosphere 3. a mechanism to trigger an updraft

Question 29

In addition to the basic requirements, what additional requirement is necessary for a severe thunderstorm to occur?

Answer 29

strong vertical wind shear

Question 30

Out of the three requirements of a thunderstorm, which is least responsible for how the storm organizes?

Answer 30

amount of moisture present

Question 31

A front, terrain features, outflow from another t-storm, and differential heating of air over surfaces with different properties are all likely to create a boundary that could result in the lifting necessary to produce a t-storm. T/F?

Answer 31

True, a strong updraft however is not likely to create one

Question 32

What spatial scale does the term "mesoscale" refer to?

Answer 32

a few to a few hundred kilometers

Question 33

What type of t-storm always rotates?

Answer 33

supercell t-storm

Question 34

what type of t-storm has an anvil?

Answer 34

all t-storms have anvils

Question 35

What type of t-storm can have an overshooting top>

Answer 35

all t-storms can have an overshooting top

Question 36

What develops when cool air generated by evaporation of rain within the downdrafts spreads outward away from the t-storm after reaching the surface?

Answer 36

gust front

Question 37

What is the term used to describe the bulge at the top of a t-storm caused by strong updrafts?

Answer 37

overshooting top

Question 38

What term describes the accumulation of rain-cooled air near the surface, under a t-storm

Answer 38

cold pool

Question 39

What t-storm feature typically forms over the gust front as warm air is lifted?

Answer 39

shelf cloud

Question 40

Most t-storms do not extend very far into the stratosphere, why?

Answer 40

because the air in the stratosphere is stable

Question 41

A downdraft in a t-storm does what?

Answer 41

results from the drag created by falling precipitation particles, and is enhanced by evaporational cooling

Question 42

A thunderstorm's anvil is composed of what?

Answer 42

ice crystals

Question 43

where do airmass t-storms tend to occur?

Answer 43

in environments where the winds do not increase substantially with height

Question 44

Where and when would you most likely see an airmass t-storm?

Answer 44

far from any frontal boundaries, 4:00 PM

Question 45

what is the primary mechanism that triggers the updraft of an airmass t-storm?

Answer 45

solar heating of the surface

Question 46

Why is wind shear a key environmental condition for severe t-storm formation?

Answer 46

Strong winds cause the updraft to tilt and separate from the downdraft, allowing the inflow of warm, moist air to continue to feed the storm.

Question 47

What type(s) of t-storms contain thunder and lightning?

Answer 47

All thunderstorms

Question 48

What type of thunderstorms form far from frontal boundaries?

Answer 48

airmass t-storms

Question 49

what type of t-storms appear as hook shaped echoes on radar reflectivity?

Answer 49

supercell t-storms

Question 50

What type of t-storms commonly form along the tail of a comma cloud associated with an extratropical cyclone?

Answer 50

frontal squall line t-storms

Question 51

what type of thunderstorms appear as a long continuous line on radar reflectivity, extending hundreds of miles?

Answer 51

frontal squall line t-storms

Question 52

what type of t-storms account for most of the large, damaging tornadoes and large hail?

Answer 52

supercell t-storms

Question 53

What type of t-storms are responsible for much of the summer rainfall on the Central Plains?

Answer 53

mesoscale convective system t-storms

Question 54

What type of t-storm has an anvil that can grow to cover an area the size of an entire U.S. state?

Answer 54

mesoscale convective systems

Question 55

What type of t-storm has an anvil and may have mammatus clouds on the underside of the anvil?

Answer 55

all t-storms

Question 56

What type of t-storms form when a low level jet helps to transport warm moist air into the storm and provides the low-level wind shear that contributes to storm rotation?

Answer 56

supercell t-storms

Question 57

What is true about a gust front?

Answer 57

it often produces a shelf cloud or a roll cloud, it can trigger new t-storm growth, and it is shallower than a t-storm

Question 58

where is the most common location for a frontal squall line to form?

Answer 58

ahead of a cold front

Question 59

what is a typical width of the region of heavy precipitation in an MCS squall line?

Answer 59

10 km

Question 60

what is a typical width of the entire precipitation region in an MCS squall line?

Answer 60

100 km

Question 61

What type of air is normally introduced into a t-storm by a rear inflow jet?

Answer 61

dry air

Question 62

what is the term used to describe eddies that develop on either end of a bow echo?

Answer 62

bookend vortices

Question 63

What feature of a t-storm sometimes appears as a fine line of lower radar reflectivity?

Answer 63

anvil

Question 64

Which of the following is true near the end of the lifecycle of an MCS?

Answer 64

the trailing stratiform region decays, leaving a large area of clouds

Question 65

what is the term used to describe the rotating region of slowly spinning clouds associated with MCS dissipation?

Answer 65

mesoscale convective vortex

Question 66

When viewing an infrared satellite image, a large, semi-circular or obling region of high clouds covering the entire state of Missouri on a July evening is most likely what t-storm system?

Answer 66

mesoscale convective system

Question 67

Along what type of front do frontal squall lines rarely form?

Answer 67

warm front

Question 68

how long is a typical frontal squall line?

Answer 68

several hundred miles

Question 69

how long does a typical frontal squall line last?

Answer 69

hours to days

Question 70

how strong can the updrafts of a supercell t-torm be?

Answer 70

approximately 100 mph

Question 71

What term is used to describe the rotating updraft within a supercell t-storm?

Answer 71

mesocyclone

Question 72

On what side of a supercell t-storm is the updraft typiclly found?

Answer 72

southwest

Question 73

what is the typical diameter of the updraft of a supercell t-storm?

Answer 73

3 to 6 miles

Question 74

which statement regarding a wall cloud is not correct?

Answer 74

it develops when the cold pool lifts warm air

Question 75

What order do you observe precipitation of a t-storm moving southwest to northeast over you?

Answer 75

virga, light rain, moderate rain, heavy rain, hail

Question 76

What features of a supercell t-storm can produce an outflow boundary and gust front?

Answer 76

forward flank downdraft, and rear flank downdraft

Question 77

In a strong t-storm, you can identify the location of the updraft by looking for what structural feature?

Answer 77

rain-free base