Fig. 10-1, p.259

1
Overshooting into stratosphere
Entrainment of air into side of cloud
tropopause
Downburst/microburst
Downdraft cuts off the updraft and kills the
convective cell
Lifetime about 1 h
Fig. 10-1, p.259
2
anvil
tropopause
Wind direction
rain
Fig. 10-2, p.260
3
Three cells in one storm
mature stage
cumulus congestus stage
cumulus stage
rain
Fig. 10-4, p.261
4
Tilted updraft is not cut off by downdraft
Fig. 10-6, p.263
5
Fig. 10-7, p.264
6
Roll cloud
Base of thunderstorm
Shelf cloud
Fig. 10-8, p.264
7
30 seconds
300 mph 8 km/min
Fig. 10-10, p.265
8
Fig. 10-9, p.265
9
Fig. 10-13, p.266
10
Fig. 10-12, p.266
11
Fig. 10-11, p.266
12
Fig. 10-14, p.267
13
Fig. 10-15, p.267
14
Fig. 10-17, p.270
15
Fig. 10-18, p.270
16
Mainly positive charge at cloud top
Large, warm hailstone becomes -ve
Mainly negative charge, except at down draft
flow of ve charge
Small, cold ice crystal becomes ve
Negative charge induces positive charge at/near
Earths surface
Fig. 10-19, p.272
17
-ve
Example of a negative cloud-to-ground stroke (90
of all lighting) initiated by a flow of electrons
from cloud base
e -

• break down electric field strength in air
  50,000 V/in
• For comparison, household voltage 120 V.
• 10 ion pairs formed per sec per cu. cm naturally
  (cosmic rays, radioactivity), which eventually
  help to transmit current (about 100,000 amps).

ve
Fig. 10-20, p.273
18
Fig. 10-22, p.274
19
Fig. 10-21, p.273
20
Fig. 10-23, p.275
21
p.276
22
Vaisala's U.S. National Lightning Detection
Network founded in Tucson, AZ. http//www.vaisala.
com/page.asp?Section32531 https//thunderstorm.va
isala.com/tux/jsp/explorer/explorer.jsp
Fig. 10-24, p.275
23
Fig. 10-5, p.262
24
downdraft
Recall tornado video
Fig. 10-33, p.284
25
Fig. 10-27, p.280
26
Fig. 10-31, p.283
27
Fig. 10-32, p.283
28
National Severe Storms Lab., Norman OK
Fig. 10-26, p.279
29
In spring/early summer the air aloft (e.g., 500
mb) is still very cold, which combined with just
a little surface solar heating, is enough to
create a very unstable atmosphere (recall
instability recipe heat from below and/or cool
from above). This is fundamentally why severe
storm/tornado season is April-June in the south.
DALR
cold
Altitude
unstable
warm
T
Table 10-1, p.281
30
Table 10-2, p.281
31
Fig. 10-29, p.282
32
Fig. 10-30, p.282
33
Fig. 10-34, p.284
34
Fig. 10-35, p.285
35
Fig. 10-36, p.286
36
Fig. 10-28, p.280
37
Fig. 10-37, p.287
38
Fig. 10-40, p.289
39
Fig. 10-CO, p.256