fig. 10-1, p.259

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

Fig. 10-26, p.279

National Severe Storms Lab., Norman OK

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