CHAPTER 6: SEVERE WEATHER AND STORM SYSTEMS Flashcards
(101 cards)
1
Q
First documented F5 tornado in Canada
A
Eli MB
2
Q
How long do microscale atmospheric systems last?
A
Only a few hours
3
Q
How long do synoptic and global atmospheric systems last?
A
Weeks-MONTHS
4
Q
A direct relationship between ___ and ___ of atmospheric systems.
A
Size and Duration
5
Q
Storm systems derive energy from (2)
A
Solar heating and condensation
6
Q
Typical time of day of tornados
A
Late afternoon
7
Q
Typical duration of tornados
A
5 mins
8
Q
Typical time of year for tornados
A
April-June
9
Q
Define Thunderstorms
A
Cumulonimbus cloud that produces lightning and thunder
10
Q
Where are thunderstorms most frequent?
A
Over tropics
11
Q
How many thunderstorms worldwide each year?
A
16 million, 2000 in progress at once
12
Q
Where do thunderstorms typically take place in USA and Canada
A
Great Plains
13
Q
Define air masses
A
Large body of air with fairly uniform temperature and moisture characteristics
14
Q
Air masses are classified based on….
A
source area
15
Q
Define Source area
A
extensive land or ocean surfaces over which an air mass derives its temperature and moisture characterics
16
Q
Latitudinal position of air masses alters the
A
Temperature
17
Q
Underlying surfaces of air masses alters the…
A
moisture
18
Q
2 possible underlying surfaces of air masses
A
C=continental(dry)
m=maritime (wet)
19
Q
5 possible latitudinal positions of air masses
A
A= ARCTIC AA= ANTARCTICA P=POLAR T= TROPICAL E= EQUATORIAL
(ACRONYM… PETA-AA)
20
Q
cA airmass is…
A
Polar high, very cold and dry
21
Q
cP airmass is…
A
polar high, cold, dryu
22
Q
mP airmass is…
A
polar high and sub polar low, humid
23
Q
cT airmass is…
A
subtropical high, hot/dry
24
Q
mT airmass is….
A
ITCZ… subtropical high/warm, humid
25
3 types of thunderstorms
1. Single-cell
2. Multicell
3. supercell
26
2 most important factors that determine thunderstorm type...
Atmospheric humidity and wind shear
27
How intense are single-cell thunderstorms?
mild and short-lived
28
Where do single-cell thunderstorms form?
within mT air masses (weak wind shear)
29
When do single-cell thunderstorms typically develop?
Late afternoon
30
Single-cell thunderstorms typically experience a predictable sequence of....
growth, maturation, and dissipation
31
Multicell thunderstorms form under what wind shear?
moderate wind shear
32
Multicell thunderstorms form along... (where in terms of air masses)
Along the fronts of air masses
33
how are multiicell thunderstorms arranged?
In clusters or squall lines
34
What is a squall line?
line of multicellular thunderstorm cells that typically form along a cold front on a midlatitude cyclone
35
What is a gust front (squall line)
Cold surge of air at ground level
36
What is a derecho?
a gust front in excess of 93km/h over a 400km area
37
Where is the forward flank in a multicellular thunderstorm?
Hot, humid side
38
Rear flank of a multicellular thunderstorm
cold, dry side
39
to be classified as a severe thunderstorms they need to have 1 or more of what 3 what conditions...
1. produce hail 2.54 cm in diameter
2. a tornado
3. wind gusts of 93km/h or greater
40
Supercell thunderstorms form over land that is...
humid and strong wind shear
41
What is a mesocyclone?
rotating column of air that is created by wind shear and updraft that may produce a tornado
42
Lightning is...
electrical discharge produced by thunderstorms
43
Thunder is...
acoustic shock wave produced when lightning rapidly heats and expands the air around it
44
What is fulgurite?
lightning infused silica sand, forms glassy hollow tube
45
What is the charge of earths upper atmosphere?
Positve
46
What is the charge of earths surface?
Negative
47
What causes lightning?
Updrafts. and downdrafts create a separation of electrical charges... opposite charges build up. 2 oppositely charged regions develop a connection and a bolt of lightning is born
48
General current of lightning?
60000 - 100000 amps
| ~80000 amps
49
How hot is lightning?
5 x hotter than sun, heats air to 30000C
50
Percentage of lightning strikes that go from cloud to ground?
20%
51
Who was Roy Sullivan?
Park ranger in Shenandoah Park, stuck by lightning 7 times.
52
How do we determine distance of lightning?
count number of seconds until thunder occurs
| - divide by 3 to get distance in Km
53
what is the 30/30 rule
- Lightning safety
| - count to 30, if thunder occurs before you get to 30, go indoors
54
Best place to be in a thunderstorm
Indoors
55
What to do if trapped outdoors in thunderstorm?
Crouch low, little amount of your body touching ground
| -or go in car
56
Define tornado
Violently rotating column of air that decsends from cumulonimbus cloud
57
What 3 storms do tornados form in?
Thunderstorms, hurricanes, cold fronts
58
what is a hook echo seen on doplar?
Likely location of tornado but not guaranteed
59
Where are the most frequent and violent tornados in North America?
Great Plains also known as Tornado Alley
60
4 ingredients that make up Tornado Alley
1. Cold Dry Air
2. Jet Stream
3. Warm Dry air
4. Warm moist air
AND LOOOW PRESSURE
61
Tornados are ranked on what scale?
Enhanced Fujita scale (EF SCALE)
62
How does the EF scale rank tornados?
Based on damage done to landscape
63
What is a tornado watch
alert issued by NWS when conditions are FAVORABLE for tornado thunderstorms
64
What is a tornado warning?
warning issued by NWS after tornado is SEEN AND CALLED IN OR SUGGESTED BY RADAR HOOK ECHO
65
What is a hurricane?
Intense travelling cyclone of tropical and subtropical latitudes, accompanied by high winds and heavy rains
66
3 Categories of Hurricans
1. Hurricanes: western... North Atlantic and north east pacific
2. Typhoons: northwest pacific... ASIA
3. Cyclone: indian ocean
67
min surface pressure needed for Hurricane
95 kpa
68
Min wind speed needed for hurricanes
119km/h
69
Where do hurricanes originate?
Warm ocean waters above 26C and between 7-15 degrees N/S
70
Peak North Atlantic hurricane season
June-Novemeber
| **PEAK ACTIVITY AUG-OCT
71
Tropical Cyclones have what 3 components?
1. calm eye
2. eyewall
3. rain bands
72
Do hurricanes need wind shear?
NO! wind shear tears hurricanes apart!
73
4 stages of a hurricane
1. Tropical Disturbance
2. Tropical Depression
3. Tropical Storm
3. HURRICANE!
74
Hurricanes are measured on which scale?
Saffir-Simpson Scale
75
Strongest hurricane wind speeds above
252 km/h
76
What guides all hurricanes
subtropical highs
77
Major cause of loss of life in a hurricane...
Storm Surge
78
What kills people in the storm surge...
drowning.. 90% of deaths are related to drowning in a hurricane
79
Storm Surge is caused by...
1. rise in sea level by strong winds
| 2. low atmospheric pressure of hurricane
80
Category 5 Hurricane creates what storm surge?
5.7m or higher
81
Atlantic Hurricanes are named after
NAMES! 6 lists that rotate.
82
What is the significance of Galveston TX hurricane in the 1900?
greatest loss of life in USA... 6000-12000
| Cateorgy 4 storm, 4.6m surge
83
What is Hurricane Katrina known for?
Costliest hurricane on record in USA
84
Which 2 USA cities are at risk for hurricane disaster?
New Orlenes and Miami
85
Define midlatitude cyclone
a low pressure system that develops in the midlatitudes
86
Where do midlatitude cyclones affect
Midlat. region of US and Canada fall-spring
87
Which are the largest storms on earth?
Midlatitude cyclones
88
Midlatitude cyclones are composed of...
warm front and cold front
89
What does the warm front do in a midlatitude cyclone?
Warm air advances on and flows over cooler and heavier air
90
What does the cold front do in a midlatitude cyclone?
Cold air advances on relatively warm air
91
Main cyclogenesis environment of midlat. cylclones
Downwind of mountain ranges and where warm water is located downwind of cold water or land surfaces
92
How long is a lifecycle of a midlat. cyclone?
1-2 Weeks
93
2 stages of midlat. cyclones
Open Wave (Separate still) or occluded (fronts combines)
94
What is a nor-easter?
midlat. cyclone that brings blizzard conditions from mid Atlantic north to New England... similar to hurricane, not as damaging
95
What are atmospheric rivers?
Narrow bands of moisture that stretch thousands of kms
| ex. pineapple express
96
What is the lake-effect snow?
A heavy snowfalls that results as cold air moves over large, warm bodies of water such as the Great Lakes
97
Surface stations in weather forecasting
over 10000 land based stations provide weather observations
98
What are radiosondes?
Weather balloons
99
What are satellites
24 hr coverage ofor weather
100
What is ensemble forecasting?
Several forecast models for the same area
101
What is quantitative forecast?
specifies the future temp, precipitation amounts, rain percentage
