1. Thunderstorms and Severe Weather
Lesson 7
Thunderstorms and Severe Weather

2. Think About It…
During which months do we get the most damaging thunderstorms here in the Piedmont?

3. 1. Average Number of Thunderstorm Days Annually… Florida is #1!!

4. 2. Cause of Thunderstorms…
Warm air rises over a mountain
Temp difference b/tw land & sea
Fronts
See next several slides for details.

5. Types of Thunderstorms…
Air Mass - Mountain
Where… within one air mass over a mountain
Why… warm air rises over a mountain, forming storm clouds!
When… midafternoon

6. Types of Thunderstorms…
Air Mass - Sea-Breeze
Where… coastal areas, esp. tropics/subtropics
Why… temperature differences between land and sea create convection cells and updrafts
When… summer

7. Types of Thunderstorms…
Types of Thunderstorms…
Frontal - Cold
Where… at the leading edge of a cold front
Why… cold air pushes warm air rapidly up at the steep cold-front boundary
When… anytime a cold front moves in!

8. Types of Thunderstorms…
Frontal – Warm
Where… at the leading edge of a warm front
Why… warm air mass slides up over a cold air mass creating clouds
When… if a warm front moves in with enough moisture and instability

9. 3. Thunderstorms in the Piedmont…
Which types of thunderstorms do we experience here in the Piedmont?
Frontal (warm and cold)
Local Air Mass (in the summer)

10. 4. Lightning… A giant spark of static electricity
4. What is lightning?
A giant spark of static electricity
How does a lightning bolt form?
A ‘-’ charge of air from a cloud (stepped leader) connects with a ‘+’ charge on the ground (return stroke).

11. Lightning… What causes thunder?
Super-heated air expanding and contracting
How hot is lightning?
30,000 degrees Celsius

12. Where is the safest place to be during a tornado?
Think About It…
Where is the safest place to be during a tornado?

13. Hail

14. 1. Tornadoes (Formation of…)
change in wind direction & speed creates horizontal rotation.
Strong updrafts tilt rotating air to vertical position.
Tornado forms within rotating winds.

15. Tornado Alley The Midwest!
2. A supercell is a giant, self-sustaining storm that can spawn tornados.
(A cP air mass from Canada meets a mT air mass from the Gulf of Mexico)
3. Tornado Alley is in the midwest.
4. Most tornadoes occur in May.

16. 5. The Enhanced Fujita Scale…
This scale is used to classify a tornado AFTER the tornado has passed by looking at the damage and effects of the tornado.
EF0 to EF5

17. The Enhanced Fujita Scale…EF0 or EF1
- Least dangerous
- % of all tornados… 80
- Path…
up to 3 miles
- Wind Speed…
mph
- Duration…
1 – 10 minutes
Dr. Theodore Fujita

18. The Enhanced Fujita Scale…EF2 or EF3
- % of all tornados… 19
- Path…
15+ miles
- Wind Speed…
mph
- Duration…
20+ minutes

19. 5c. The Enhanced Fujita Scale…EF4 or EF5
- Most dangerous!!
- % of all tornados…
1 (Thankfully!)
- Path…
50+ miles
Wind Speed…
200+ mph
Duration…
1+ hours

20. Tornado Safety…
Move to a pre-designated shelter – to a basement if possible.
Move to an interior room/hall, lowest floor, under sturdy furniture. (A bath tub is safest!)
Stay away from windows.
Get out of vehicles!
Don’t try to outrun a tornado.
If outside, lie flat in a ditch or depression.
Abandon a mobile home for a shelter.

21. Tropical Storms & Hurricanes
Lesson 8
Tropical Storms & Hurricanes

22. Tropical Cyclones… Large, rotating, low pressure storm hurricanes
A tropical cyclone can be described as a…
Large, rotating, low pressure storm
2. We call these storms…
hurricanes
3. Tropical cyclones derive energy from…
Warm, tropical oceans

23. Fran, 1996, Cape Fear, NC Name was retired!
Tropical Cyclones…
Which direction do tropical cyclones turn in the northern hemisphere?
Counterclockwise
It is a low pressure system!
Remember the Coriolis effect?
Fran, 1996, Cape Fear, NC Name was retired!

24. Tropical Cyclones… Air pressure in eyewall– decreases
As a hurricane strengthens, what do the following components do?
Air pressure in eyewall– decreases
Surface wind speeds – increase

25. Tropical Cyclones… the west! the prevailing westerlies
6. Tropical cyclones in the N. Hemisphere move steadily towards…
the west!
7. Which wind system moves across the USA and usually guides hurricanes out into the Atlantic Ocean?
the prevailing westerlies
Hurricane Rita – 2005, 3rd lowest pressure in Atlantic (897 mb), hit as cat. 3

26. 8. Development of a Tropical Cyclone…
Tropical Disturbance – a weak, low-pressure system – group of thunderstorms collect

27. Development of a Tropical Cyclone…
Development of a Tropical Cyclone…
Tropical Depression – a disturbance begins to rotate around the center of low pressure

28. Development of a Tropical Cyclone…
Development of a Tropical Cyclone…
Tropical Storm – a depression is labeled a storm when the wind speeds reach 39 mph.
Tropical Storm Dalila, July 2007

29. Development of a Tropical Cyclone…
Development of a Tropical Cyclone…
Tropical Hurricane – pressure drops and the wind speeds reach 74 mph
Dean 2007
Katrina 2005
Ivan2006

30. Hurricane History…

31. 9. Anatomy of a Hurricane…
9. Anatomy of a Hurricane…

32. Classifying Hurricanes… The Saffir-Simpson Scale
characteristics of a hurricane described…
Wind speed – how high?
Air pressure – how low?
Potential for damage – how much?!
Storm surge

33. Classifying Hurricanes…
2. The Saffir-Simpson Scale…
Categories 1 – 5
Category that does the most damage – 5
Wind speed of a cat 5? > 155 mph
Three most powerful storms to hit USA?
Florida Keys, 1935
Camille, 1969
Andrew, 1992

34. Classifying Hurricanes…
3. A hurricane runs out of energy
When it moves over land or cold water

35. Hurricane Hazards… eye wall
1. The strongest winds in a hurricane are in the…
eye wall

36. Hurricane Hazards…
2. What is a storm surge?
When hurricane force winds drive a mound of ocean water towards coastal areas

37. Storm Surge…
9 of every 10 people who die in a hurricane are killed by the storm surge.
You should EVACUATE so you don’t get killed by the storm surge!

38. Flooding from Hurricane Fran
Hurricane Hazards…
3. What hurricane hazard is caused by great amounts of rain?
floods
Flooding from Hurricane Fran

39. Hurricane Hazards… The National Hurricane Center in Miami, FL
4. Which agency is responsible for tracking and forecasting hurricanes?
The National Hurricane Center in Miami, FL
(FIU Campus) (NOAA)

40. The World’s Best Hurricane Safety Tip…
EVACUATE!!

41. Human Impact on Air Quality
Lesson 9
Human Impact on Air Quality

42. Smog (Smokey Fog)… Smog is a yellow-brown photochemical haze.
Smog is caused by solar radiation heating pollution (hydrocarbons & nitrogen oxides mostly from car exhaust).
Smog makes it difficult to breathe!
The major chemical in smog is ozone.
b/c Ozone irritates the eyes, nose, throat, & lungs.
See next slide…

43. Particulate Matter… Four examples of particulate matter include…
ash, dust, pollen, & asbestos fibers.
These are forms of SOLID pollutants in the air.
Particulate matter is harmful to people because it can…
get in lung tissues & cause breathing difficulties & lung disease.
See next slide…

44. Particulate Matter (Draw in margin.)

45. Review Only! The Greenhouse Effect
What is the greenhouse effect? It is heat from the sun being trapped by the gases in our atmosphere.
A greenhouse effect you may relate to is that of a closed car on a cold, sunny day in winter.
The greenhouse effect is a GOOD thing! It allows for life on our planet!

46. Global Warming…
1. Global warming is…
… an increase in Earth’s average surface temperature.
2. Some scientists believe that the cause of global warming is...
… the burning of fossil fuels
Write examples in margin…
which releases carbon dioxide (CO2)
CO2 makes up only .04% of the atmosphere! (4 out of 10,000 molecules)
Coal for electricity
Gasoline for vehicles
Natural Gas for fireplaces and cooking

47. Add to Margin of Notes…Fossil Fuel Use
Fossil Fuels Used…
Coal for electricity
Gasoline for vehicles
Natural Gas for fireplaces and cooking
3. There are many scientists who believe the Sun has the major role in global warming/cooling.
4. To reduce levels of CO2 in the atmosphere people can …
… reduce our use of fossil fuels! (And stop breathing!) How?

48. The Ozone Issue 1. Ozone absorbs ultraviolet radiation from the sun.
Review! The ozone layer is found in the stratosphere.
1. Ozone absorbs ultraviolet radiation from the sun.

49. The Ozone Issue
This diagram illustrates what a “hole” in the ozone might look like.

50. Add to Margin of Notes: 3 Effects of Ultraviolet Radiation…
Ultraviolet radiation from the sun can cause cataracts (a clouding of the lens of the eye) and skin cancer.
Ultraviolet radiation can kill the eggs of certain animals like amphibians because they lay their eggs in shallow water.

51. The Ozone Issue Review… The chemical formula for ozone is O3
Draw this in the margin of your Lesson!

52. The Ozone Issue
2. Man-made chemicals called (CFCs) chlorofluorocarbons react with ozone and break it apart.
(The part of the CFC molecule that reacts with the ozone molecule is the chlorine atom.)
observe.arc.nasa.gov

53. The Ozone Issue
3. CFCs are used as refrigerants, coolants, propellants in aerosol cans, and Styrofoam.
tiki.oneworld.net

54. 4. How CFCs destroy ozone…

55. The Ozone Issue
5. We should eliminate sources of CFCs worldwide. (CFCs were banned in the late 1980’s in industrialized nations. They are still in use in some places in the world.)
“Under the 1987 Montreal Protocol, developing countries committed themselves to halving consumption and production of the CFCs by 2005 and to achieving an 85 percent cut by 2007.”

56. Acid Precipitation (Rain)…
1. Acid precipitation (rain) is precipitation with a pH of less than 5.
The pH of natural precipitation is 5.0 to 5.6.
2. Acid precipitation forms when sulfur dioxide (SO2) & nitrogen oxides (NO2) combine w/ atmospheric water to create sulfuric acid & nitric acid.
3. Six types of acid precipitation are acidic rain, snow, fog, mist, gas, and dust.
Nitrous oxide and sulfur dioxide come from
volcanoes, marshes, and human activities 56

57. Easy on the acid rain, guys!
6. Three effects of acid precipitation are the damage it causes to…
… aquatic ecosystems
… plants & soil.
… stone buildings & statues. 57

58. (to reduce sulfur emissions)
Acid Rain…
7. Prevention:
Use wet scrubbers on smoke stacks of coal-burning power plants.
(to reduce sulfur emissions) 58