1.
Thunderstorms
(pg. 263)
1.
“Ordinary” thunderstorm
(Fig. 10.1-10.2).
·
Lifecycle =
cumulus – mature – dissipating
·
Convective
cell, updraft, downdraft, gust
front, entrainment, overshooting.
·
Lifetime of
about 1 hour; terminating when
downdraft cuts off the updraft.
·
Multi-cell
storms are common (Figure 10.3).
·
Other
features:
·
Gust front,
downburst (Fig. 10.10), shelf
cloud.
·
Can form
along a front, ahead of a front, along a dryline (Fig. 10.9).
·
Can lead to
flash floods.
· “Climatology” (Fig. 10.18-10.19)
Afternoon thunderstorm over Santa Catalina mountains (video clip; fast forward to 16:00:00)·
“Severe” thunderstorm –
includes ¾ inch hail.
·
Tilting due
to strong winds prevents
updraft from being cut off (Fig. 10.10) allowing storm to develop for a
long
period of time and become severe (intense).
·
Supercells
can develop that might spawn
tornadoes (Fig. 10.4)
· Organization
"Linear" Squall Lines
· Along fronts, prefrontal, dry lines (Fig. 10.9)
"Circular" Mesoscale Convective Systems (MCS)
·
Huge
(mesoscale) system of thunderstorms (Fig. 10.8)
2.
Lightning and
Thunder (page 277)
·
Cloud electrification
(negative charge most often accumulates at
bottom; Fig. 10.21)
§
Stepped leader
(invisible) moves toward the ground where it is joined by upward moving postitive ions (Fig. 10.22).
§
Negative and postive stepped leader channels join and then return stroke (visible)
rises from the ground resulting in cloud-to-ground lightning
flash(es).
§
Also get cloud-to-cloud
lightning (sheet lightning)
·
Professor Krider; National Lightning
Detection and Location (Vaisala,
Triggered lightning video clip
· Horizontal vortex tube becomes vertical tube when lifted by updraft of severe thunderstorm (Fig. 10.34).
·
Common features (Fig.
10.30, 10.31, 10.35, 10.37).
·
“Climatology” (Fig. 10.28)
