fig. 10-1, p.259
DESCRIPTION
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. anvil. tropopause. Wind direction. rain. Fig. 10-2, p.260. - PowerPoint PPT PresentationTRANSCRIPT
Fig. 10-1, p.259
Lifetime about 1 h
Overshooting into stratosphere
Entrainment of air into side of cloud
tropopause
Downburst/microburstDowndraft cuts off the updraft and “kills” the convective cell
Fig. 10-2, p.260
anvil
Wind direction
tropopause
rain
Fig. 10-4, p.261
cumulus stage
cumulus congestus stage
mature stage
rain
Three cells in one storm
Fig. 10-6, p.263
Tilted updraft is not cut off by downdraft
Fig. 10-7, p.264
Fig. 10-8, p.264
Roll cloud Shelf cloud Base of thunderstorm
Fig. 10-10, p.265
300 mph = 8 km/min
30 seconds
Fig. 10-9, p.265
Fig. 10-13, p.266
Fig. 10-12, p.266
Fig. 10-11, p.266
Fig. 10-14, p.267
Fig. 10-15, p.267
Fig. 10-17, p.270
Fig. 10-18, p.270
Fig. 10-19, p.272
Mainly negative charge, except at down draft
Mainly positive charge at cloud top
Negative charge induces positive charge at/near Earth’s surface
Large, “warm” hailstone becomes ve
Small, “cold” ice crystal becomes +ve
flow of +ve charge
Fig. 10-20, p.273
• “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).
+
e
+ve
ve
Example of a negative cloud-to-ground stroke (90% of all lighting) initiated by a flow of electrons from cloud base
Fig. 10-22, p.274
Fig. 10-21, p.273
Fig. 10-23, p.275
p.276
Fig. 10-24, p.275
Vaisala's U.S. National Lightning Detection Network founded in Tucson, AZ.
http://www.vaisala.com/page.asp?Section=32531
https://thunderstorm.vaisala.com/tux/jsp/explorer/explorer.jsp
Fig. 10-5, p.262
Fig. 10-33, p.284
downdraft
Recall tornado video
Fig. 10-27, p.280
Fig. 10-31, p.283
Fig. 10-32, p.283
Table 10-1, p.281
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
T
Alti
tude
cold
warmunstable
Table 10-2, p.281
Fig. 10-29, p.282
Fig. 10-30, p.282
Fig. 10-34, p.284
Fig. 10-35, p.285
Fig. 10-36, p.286
Fig. 10-28, p.280
Fig. 10-37, p.287
Fig. 10-40, p.289
Fig. 10-CO, p.256