Class #9: Monday, July 19 Thunderstorms and tornadoes Chapter
14 1Class #9, Monday, July 19, 2010
Slide 2
Fig. 14-CO, p. 370 2Class #9, Monday, July 19, 2010
Slide 3
Fig. 14-1, p. 372 3Class #9, Monday, July 19, 2010
Slide 4
Thunderstorms and Tornadoes Chapter 14 4Class #9, Monday, July
19, 2010
Slide 5
Thunderstorms A storm containing lightening and thunder;
convective storms Severe thunderstorms: one of large hail, wind
gusts greater than or equal to 50kts, or tornado Ordinary Cell
Thunderstorms Air-mass thunderstorms: limited wind sheer Stages:
cumulus, mature, dissipating Entrainment, downdraft, gust front
5Class #9, Monday, July 19, 2010
Slide 6
6
Slide 7
Fig. 14-2, p. 373 7Class #9, Monday, July 19, 2010
Slide 8
Fig. 14-2, p. 373 8Class #9, Monday, July 19, 2010
Slide 9
Fig. 14-2, p. 373 9Class #9, Monday, July 19, 2010
Slide 10
10Class #9, Monday, July 19, 2010
Slide 11
Fig. 14-4, p. 375 11Class #9, Monday, July 19, 2010
Slide 12
Thunderstorms Multi-cell Thunderstorms Thunderstorms that
contain a number of convection cells, each in a different stage of
development, moderate to strong wind shear; tilt, over shooting top
Gust Front: leading edge of the cold air out-flowing air; shelf
cloud, roll cloud, outflow boundary Micro-bursts: localized
downdraft that hits the ground and spreads horizontally in a radial
burst of wind; wind shear, virga 12Class #9, Monday, July 19,
2010
Slide 13
13Class #9, Monday, July 19, 2010
Slide 14
Fig. 14-6, p. 376 14Class #9, Monday, July 19, 2010
Slide 15
15Class #9, Monday, July 19, 2010
Slide 16
16Class #9, Monday, July 19, 2010
Slide 17
17Class #9, Monday, July 19, 2010
Slide 18
Thunderstorms Multi-cell Thunderstorms Squall-line
thunderstorms; line of multi-cell thunderstorms, pre-frontal
squall-line, derecho Meso-scale Convective Complex: a number of
individual multi-cell thunderstorms grow in size and organize into
a large circular convective weather system; summer, 10,000km 2
18Class #9, Monday, July 19, 2010
Slide 19
Fig. 14-10, p. 378 19Class #9, Monday, July 19, 2010
Slide 20
Fig. 14-11, p. 378 20Class #9, Monday, July 19, 2010
Slide 21
Stepped Art Fig. 14-11, p. 378 21Class #9, Monday, July 19,
2010
Slide 22
22Class #9, Monday, July 19, 2010
Slide 23
23Class #9, Monday, July 19, 2010
Slide 24
24Class #9, Monday, July 19, 2010
Slide 25
25Class #9, Monday, July 19, 2010
Slide 26
26Class #9, Monday, July 19, 2010
Slide 27
27Class #9, Monday, July 19, 2010
Slide 28
Thunderstorms Supercell thunderstorms Large, long-lasting
thunderstorm with a single rotating updraft Strong vertical wind
shear Outflow never undercuts updraft Classic, high precipitation
and low precipitation supercells Cap and convective instability
Rain free base, low-level jet Surface, 850mb, 700mb, 500mb, 300mb
conditions 28Class #9, Monday, July 19, 2010
Slide 29
29Class #9, Monday, July 19, 2010
Slide 30
30Class #9, Monday, July 19, 2010
Slide 31
31Class #9, Monday, July 19, 2010
Slide 32
32Class #9, Monday, July 19, 2010
Slide 33
33Class #9, Monday, July 19, 2010
Slide 34
Fig. 14-23, p. 384 34Class #9, Monday, July 19, 2010
Slide 35
Thunderstorms Thunderstorms and the Dryline Sharp, horizontal
change in moisture Thunderstorms form just east of dryline cP, mT,
cT Floods and Flash Floods Flash floods rise rapidly with little or
no advance warning; many times caused by stalled or slow
thunderstorm Large floods can be created by training of storm
systems, Great Flood of 1993 35Class #9, Monday, July 19, 2010
Slide 36
Fig. 1, p. 386 36Class #9, Monday, July 19, 2010
Slide 37
37Class #9, Monday, July 19, 2010
Slide 38
Thunderstorms Topic: Big Thompson Canyon July 31, 1976, 12
inches of rain in 4 hours created a flood associated with
$35.5million in damage and 135 deaths Distribution of Thunderstorms
Most frequent Florida, Gulf Coast, Central Plains Fewest Pacific
coast and Interior valleys Most frequent hail Central Plains
38Class #9, Monday, July 19, 2010
Slide 39
Fig. 14-25, p. 387 39Class #9, Monday, July 19, 2010
Slide 40
40Class #9, Monday, July 19, 2010
Slide 41
41Class #9, Monday, July 19, 2010
Slide 42
Thunderstorms Lightening and Thunder Lightening: discharge of
electricity in mature storms (within cloud, cloud to cloud, cloud
to ground) Thunder: explosive expansion of air due to heat from
lightening Electrification of Clouds: graupel and hailstones fall
through supercooled water, ice crystals become negatively charged
Upper cloud positive, bottom cloud negative 42Class #9, Monday,
July 19, 2010
Slide 43
43Class #9, Monday, July 19, 2010
Slide 44
Fig. 2, p. 390 44Class #9, Monday, July 19, 2010
Slide 45
45Class #9, Monday, July 19, 2010
Slide 46
46Class #9, Monday, July 19, 2010
Slide 47
Thunderstorms Observations: Elves Blue jets, red sprite, ELVES
The Lightening Stroke Positive charge on ground, cloud to ground
lightening Stepped leader, ground stroke, forked lightening, ribbon
lightening, bead lightening, corona discharge 47Class #9, Monday,
July 19, 2010
Slide 48
48Class #9, Monday, July 19, 2010
Slide 49
Thunderstorms Observation: Apple tree DO NOT seek shelter
during a thunderstorm under an isolated tree. Lightening Detection
and Suppression Lightening direction finder detects radiowaves
produced by lightening, spherics National Lightening Detection
Network Suppression: seed clouds with aluminum 49Class #9, Monday,
July 19, 2010
Slide 50
50Class #9, Monday, July 19, 2010
Slide 51
Fig. 14-32, p. 392 51Class #9, Monday, July 19, 2010
Slide 52
Fig. 14-33, p. 393 52Class #9, Monday, July 19, 2010
Slide 53
Fig. 14-34, p. 393 53Class #9, Monday, July 19, 2010
Slide 54
Fig. 14-35, p. 394 54Class #9, Monday, July 19, 2010
Slide 55
Fig. 14-36, p. 394 55Class #9, Monday, July 19, 2010
Slide 56
Fig. 3, p. 395 56Class #9, Monday, July 19, 2010
Slide 57
Fig. 14-37, p. 396 57Class #9, Monday, July 19, 2010
Slide 58
58Class #9, Monday, July 19, 2010
Slide 59
Tornadoes Rapidly rotating column of air that blows around a
small area of intense low pressure with a circulation that reaches
the ground. Tornado life cycle Organizing, mature, shrinking, decay
stage Tornado outbreaks Families, super outbreak 59Class #9,
Monday, July 19, 2010
Slide 60
Tornadoes Tornado Occurrence US experiences most tornadoes
Tornado Alley (warm, humid surface; cold dry air aloft) Highest
spring, lowest winter Tornado winds Measurement based upon damage
after storm or Doppler radar For southwest approaching storms,
winds strongest in the northeast of the storm, 220 kts maximum
Multi-vortex tornados 60Class #9, Monday, July 19, 2010
Slide 61
61Class #9, Monday, July 19, 2010
Slide 62
62Class #9, Monday, July 19, 2010
Slide 63
63Class #9, Monday, July 19, 2010
Slide 64
64Class #9, Monday, July 19, 2010
Slide 65
Tornadoes Seeking shelter Basement or small, interior room on
ground floor Indoor vs. outdoor pressure The Fujita Scale Based
upon the damage created by a storm F0 weakest, F5 strongest
Enhanced Fujita Scale 65Class #9, Monday, July 19, 2010
Slide 66
Tornadic Formation Basic requirements are an intense
thunderstorm, conditional instability, and strong vertical wind
shear Supercell Tornadoes Wind sheer causes spinning vortex tube
that is pulled into thunderstorm by the updraft Mesocyclone, BWER,
rear flank downdraft, vertical stretching, funnel cloud, rotating
cloud, wall cloud 66Class #9, Monday, July 19, 2010
Slide 67
Table 14-1, p. 399 67Class #9, Monday, July 19, 2010
Slide 68
Table 14-2, p. 400 68Class #9, Monday, July 19, 2010
Slide 69
Table 14-3, p. 400 69Class #9, Monday, July 19, 2010
Slide 70
Fig. 14-42, p. 400 70Class #9, Monday, July 19, 2010
Slide 71
Fig. 14-43, p. 401 71Class #9, Monday, July 19, 2010
Slide 72
72Class #9, Monday, July 19, 2010
Slide 73
73Class #9, Monday, July 19, 2010
Slide 74
74Class #9, Monday, July 19, 2010
Slide 75
Stepped Art Fig. 14-46, p. 402 75Class #9, Monday, July 19,
2010
Slide 76
Tornadic Formation Nonsupercell Tornadoes Gustnadoes Land spout
Cold-air funnels 76Class #9, Monday, July 19, 2010
Slide 77
77Class #9, Monday, July 19, 2010
Slide 78
78Class #9, Monday, July 19, 2010
Slide 79
Severe Weather and Doppler Radar Doppler radar measures the
speed of precipitation toward and away radar unit Two Doppler
radars can provide a 3D view TVS, Doppler lidar NEXRAD 79Class #9,
Monday, July 19, 2010
Slide 80
Fig. 14-49, p. 405 80Class #9, Monday, July 19, 2010
Slide 81
Fig. 14-50, p. 405 81Class #9, Monday, July 19, 2010
Slide 82
Fig. 14-51, p. 406 82Class #9, Monday, July 19, 2010
Slide 83
Waterspouts Rotating column of air that is connected to a
cumuliform cloud over a large body of water Tornadic waterspout
83Class #9, Monday, July 19, 2010
Slide 84
Fig. 14-52, p. 409 84Class #9, Monday, July 19, 2010
