Thunderstorms

Florida has more thunderstorms each year than anywhere else in the US

Hail

The western great Plains has more Hail storms each year than anywhere else in the US

Tornadoes

Although Florida also has lots of tornadoes per 10000 square miles most of these are F0 to F2. The central plains have the most tornadoes each year.

Electrons have negative charge and protons have positive charge.

Opposite charges attract each other and similar charges repel each other

Pick up a piece of paper with a comb. Although the paper does not have a total positive or negative charge the charges on it are shifted around so that the + charge on the paper is closer to the – charge on the comb. The paper is attracted to the comb.

A balloon sticks to the wall. Although the wall does not have a total positive or negative charge the charges on it are shifted around so that the + charge on the wall is closer to the – charge on the balloon. The Balloon is attracted to the wall.

Polarization of a molecule in the bottom figure

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

Normally the upper part of a cloud is positively charged and the bottom is negatively charged.

Thunderstorms

• The Lightening Stroke– Positive charge typically on ground, cloud to

ground lightening– Stepped leader, ground stroke, forked

lightening, ribbon lightening, bead lightening, corona discharge

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

Fig. 3, p. 395

Fig. 14-32, p. 392

Sferics

http://www.lightningsafety.com/nlsi_lls/fatalities_us.html

StateDeath Rate/

Million Rank

Wyoming 2.02     1

Utah 0.70     2

Colorado 0.65     3

Florida 0.56     4

Montana 0.55     5

New Mexico 0.55     6

South Dakota 0.47     7

Idaho 0.39     8

Alabama 0.38     9

Louisiana 0.37   10

Lightning Deaths in the United States Weighted by Population, 1990 to 2003

Location of Incident:

40% Unreported.

27% Open fields & recreation areas (not golf).

14% Under trees (not golf).

8% Water-related (boating, fishing, swimming…).

5% Golf/golf under trees.

3% Heavy equipment and machinery-related.

2.4% Telephone-related.

0.7% Radio, transmitter & antenna-related.

2. Gender of victims = 84% male; 16% female.

3. Months of most incidents = June 21%, July 30%, Aug 22%.

4. Days of week of most incidents = Sun./Wed./Sat.

5. Time of day of most incidents = 2 PM to 6 PM.

6. Number of victims = One (91%), two or more (9%).

7. Deaths by State, Top Five = FL, MI, TX, NY, TN.

8. Injuries by State, Top Five = FL, MI, PA, NC, NY.

"If you can see it, flee it; If you can hear it, clear it.“

http://www.lightningsafety.com/nlsi_pls/decision_tree_people.html

Thunderstorms

• Observations: TLEs Transient Luminous Events – Blue jets, red sprite, ELVES

Fig. 2, p. 390