Chapter 13 Answer questions as we go along!

Life Cycle of a Thunderstorm Developing Stage a.Towering cumulus cloud indicates rising air. b.Usually little if any rain during this stage. c.Lasts about 10 minutes. d.Occasionally lightning during this stage. Q1

Life Cycle of a Thunderstorm Mature Stage a.Most likely time for heavy rain, frequent lightning, strong winds, and tornadoes. b.Storm occasionally has a black or dark green appearance. c.Lasts an average of 10 to 20 minutes but may last much longer in some storms. Q1

Life Cycle of a Thunderstorm Dissipating Stage a.Rainfall decreases in intensity. b.Some thunderstorms produce a burst of strong winds during this stage. c.Lightning remains a danger during this stage. Q1

Lightning Formation

“A Bolt out of the Blue” Lightning can strike up to 25 miles away!!!! Why you can’t swim until at least half an hour after the last thunder rumbles

Lightning Stats and Safety State with the most lightning strikes: FL People most commonly hit by lightning: park rangers and golfers Q2

Thunder (skip down to question 7) Lightning superheats the air Air expands faster than the speed of sound Creates a sonic boom Every 5 seconds counted between lightning and thunder = 1 mile to lightning bolt

Fulgurites Lightning hits sand or concrete (made of mostly sand) Brittle hollow tube Like melted glass

Cold Fronts: Squall Lines Q3

Cold Fronts: Squall Lines

Squall Lines Chains of thunderstorms Form along cold fronts as they advance Can be accompanied by severe weather such as tornadoes, hail and strong winds Q3-4

Super Cells! Can form along a cold front Sometimes form as a single celled storm Q5

Super Cells Features: –Anvil top –Overshooting top –Wall Cloud –Often, tornado or hail One, very large storm cloud. Caused by extreme heating during the day Q5-6

Wall Cloud

Tornadoes! Q8

Where do most tornadoes form? Tornado Alley: –Midwest US –cP air meets mT air More tornadoes here than anywhere else in the world

Tornado Summary

How do mid-west tornadoes form? 3 layers in the atmosphere: –cP off Rockies –cT off Mexican Plateau –mT off Gulf of Mexico Arranged from least dense on the bottom to most dense on top “Dry line” is critical to tornado formation

Judging Tornado Strength: The Fujita Scale The Fujita Scale Based on wind speeds over a 3 second gust Based on damage Q9, 10

Tornado Damage

F0 F1 F2 F3

F4 F5

Tornado Safety Q 11

Common East Coast Tornado Radar Signature: Storm Relative Velocity Image Inbound and outbound winds Red: moving towards radar Green: moving away radar

Stafford, VA Tornadoes (2011) Tuscaloosa, AL tornado (long video – skip along!)Tuscaloosa, AL tornado

29 Pictures from tornado damage in Stafford Thursday 5/8/08

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35 NATIONAL WEATHER SERVICE CONFIRMS F2 TORNADO HIT

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Stafford Tornado Clouds! 6/4/08

One year later…

Hail from 6/3/09 Clumping of smaller hailstones Layers formed as hail is lifted in an updraft, partially melts, then refreezes

Why does hail form in the summer?

Tropical Cyclones Hurricanes are large scale cyclones of tropical origin Q 12 Hurricanes 101

Hurricane Features Eye Eye Wall Feeder Bands What direction do they rotate in the N. Hemi? Why? Q 14-16

Q 17

Tropical Cyclones: Hurricanes and Typhoons Hurricane BeltsWhere? Why? Q 13-23

Tropical Cyclones: Hurricanes and Typhoons Hurricane BeltsWhere? Why? “Hurricanes” “Typhoons” “Typhoon” Q 13-23

Tropical Cyclones: Hurricanes and Typhoons Hurricane BeltsWhere? Why? Beyond 20 or 30 N/S: Water is too cold for tropical cyclones to form. “Hurricanes” “Typhoons” “Typhoon” Equator: Coriolis Effect is too weak – No Hurricanes Beyond 20 or 30 N/S: Water is too cold for tropical cyclones to form. Q 13-23

Hurricane Facts Wind Speeds Depression = 38 mph Trop storm = mph Hurricane = 74 mph “Hurricane Season” June 1- Nov 30 Q

Hurricane Damage Winds –VERY strong Flooding –Biggest cause of death –Storm Surge can be up to 30 feet –Caused by combined rotation of winds and the bulldozing of the ocean waters Q 26

Saffir Simpson Scale Q 27

Hurricane Naming Naming:Naming –Alphabetical –Alternate male/female –Names retired if destructive Q 28

Most Severe US Hurricanes Katrina: –$90.9 billion (US, 2009) Day by dayDay by day Subsidence of a CitySubsidence of a City Andrew: –$41 billion (US, 2009) Super Cyclone Phailin (2013)

Superstorm Sandy Combo of hurricane and a nor’easter!

“Superstorm” Sandy (2012) Largest Atlantic Hurricane on Record (diameter >1,000 miles) Manhattan Power Outage Subway system

“Snowmaggedon” 2010

Blizzards Requirements to be a blizzard? –Winds of 35 mph for 3+ hrs –Visibility of less than ¼ mile Nor’easters –Winter storms on the east coast that come from the northeast Thundersnow!Thundersnow Q 29-30