Severe Weather Guided Notes
1. ____________________ - current state of the atmosphere. ________________________- describes the
average weather over a long period of time
2. Thunderstorms are most often associated with a __________________________________ cloud. This is a
cloud that forms when air is forced high into the atmosphere (against its will). Cold fronts often create this
condition. This produces an ___________________________ environment. The process of cooling,
condensing, cloud formation, saturation and precipitation occurs quickly. ____________ fronts often create
the proper conditions for this to occur
3. Three Types of Thunderstorms
a. ________ __________ thunderstorm-results from air rising due to unequal heating in an air mass.
b. ______ breeze thunderstorms result from extreme temperature differences air over land & water.
c. ______________________ thunderstorms-results from advancing cold fronts.
4. For a thunderstorm to form, three conditions must exist.
a. Abundant source of ________________________
b. Mechanism to _______________ air so that the moisture can condense and release latent heat.
c. ___________________________________ in the atmosphere
5. Cumulus Stage - Air ___________ vertically. Moisture _____________________
into visible cloud. The height at which condensation occurs is called lifted
condensation level (LCL). _____________________________ occurs.
6. Mature Stage - Precipitation falls, _____________________ the air surrounding
it and creating a downdraft. Strong updraft of warm, moist air, AND a strong
downdraft of wind and precipitation. Equal amount of updraft and downdraft
creates a cumulonimbus cloud.
7. Dissipation Stage - The surface has been _________________________, cutting off the warm, moist air that
“fuels” the storm. _________________________ ceases. Lingering downdraft persists. Once the
precipitation has fallen from the sky, the storm is over
8. The air in a thunderstorm will keep rising until:
a. ______________________ air is reached that it cannot overcome
b. Rate of condensation is not able to generate enough latent _____________________ to keep the
cloud warmer than the surrounding air
9. Lightning is believed to be created by ___________________ between the rising updraft and the falling
downdraft in a cumulonimbus cloud. This friction creates a separation of charges (like rubbing your feet
across the carpet in your socks). Eventually there is a _____________________ between positive and
negative charges, creating a “spark” (like touching that doorknob and getting a shock). On a larger scale,
that “__________________” is a bolt of lightning
10. When lightning strikes, the “bolt” can be as hot as 30,000 degrees. The air surrounding that bolt of
electricity __________________ rapidly (remember… warm air expands), and then contracts quickly as it
cools. Because of the extremely high temperatures involved, the air __________________ and
__________________ rapidly enough to break the sound barrier (767 mph). The thunder is a “sonic boom”
11. What goes up, must come down! Thunderstorms are no different, when _______________ air rises high into
the atmosphere, it eventually cools and comes back down toward the surface. Cumulonimbus clouds can be
as tall as 40,000 feet, so…they can fall very quickly toward the surface, producing strong
__________________ (called downdrafts)
12. A _______________________ is a violent, whirling column of air
in contact with the ground. Before touching ground it is called a
funnel cloud.
13. Because of the lower _____________________ in the center
vortex, air near the ground rushes into the tornado from all
directions. Air streams inward, it is spiraled
___________________ around the core until it eventually merges
with the airflow or the parent thunderstorm deep in a
cumulonimbus tower.
14. Less than _______% of thunderstorms produce tornadoes. Most
intense tornadoes are associated with supercells (big, cumulonimbus cloud structures).
15. Tornadoes are visible due to dust, debris, and condensation. Created when wind speed and direction
change suddenly with height, a process called wind shear.
16. Tornadoes are classified using the Fujita Intensity Scalea. Assesses the damage produced by a storm as it relates to wind speed.
i. F0- Moderate; 40-72 mph
ii. F5- Severe; 261-318 mph
b. Path of Destruction
c. Duration
d. Problem: Doesn’t take into account for structural integrity of objects.
17. The ENHANCED Fujita Scale (EF – Scale) is now used in the US. It DOES take into account structural damage
(but still uses a 0-5 numerical scale)
18. Tornado _______________ – Conditions are ideal for a tornado to be created. Tornado ________________
– An actual tornado has been sighted in the area or is indicated by weather ________________.
19. We give different names to Tropical Storms that develop, depending on their location. In the Atlantic Ocean
we call them _____________________. In the Pacific Ocean we call the _______________________. In the
Indian Ocean we call them _______________________. They are all basically the same type of storm.
20. Tropical cyclones are large, rotating, ________-pressure storms that form over water during summer and
fall in the tropics. Two things to form:
a. Abundance of __________________ water
b. Disturbance to __________________ air and keep it rising
21. The hurricanes that strike the Caribbean, Gulf of Mexico and the US originate in _____________________.
They begin as _______________ pressure storm systems over land. The ________________ Winds (one of
the systems of global winds) blow them out over the ____________ water of the Atlantic Ocean.
22. Remember that __________ pressure pulls air in at the surface and pushes it to higher levels in the
atmosphere. Air temperatures at high levels in the atmosphere are _______________, and the warm, moist
air over the ocean begins to form ________________ (BIG Cumulonimbus clouds). Lots of Latent Heat
released during _________________________. Creates a very ______________________ environment.
23. Remember that the water over the Atlantic Ocean near Africa is warm (_____°F) and has lots of
_____________________ in it (___________ air masses). As precipitation begins, the rain and cool downdrafts of the Cumulonimbus system are not enough to cut off the updraft (it’s too warm). The warm,
_______________ air continues to fuel the system of Cumulonimbus clouds, making them bigger, & bigger.
24. Once the growing ________ _____________________ system is out over the warm water of the Atlantic
Ocean, the __________________________ Winds blow it to the west. Because the oceans are relatively
smooth, there isn’t much to stand in its way and slow it down. With 2,000 to 3,000 miles of warm ocean
water to move across…the system has the time and the fuel to become __________________________.
25. Low pressure begins as a Tropical Disturbance. The low-pressure systems that blow out over the waters of
the Atlantic Ocean begin as Tropical ________________________________ (a low pressure system is in fact
a “depression” of pressure). If winds in the system reach 39mph, the system becomes classified as a Tropical
____________________________ (& given a name). If the system continues to gain strength and winds
speeds reach 74 mph, it is officially classified as a ____________________________.
26. The most dangerous component of a hurricane is the “_____________ ________________”. As the storm
makes landfall, a mound of ocean water (driven by strong winds AND the “sucking” power of the strong low
pressure system) is pushed on shore. More people die as a result of drowning, than do of strong winds
27. _______________-calm center of the storm.
______________________-band immediately
surrounding the eye that contains the strongest
winds in a hurricane. A hurricane will last until it can
no longer produce enough energy to sustain itself.
This usually happens when:
a. Hurricane runs over ________________
b. Hurricane runs into _________________
water
28. As a hurricane makes landfall, the supply of warm,
__________________ air that was fueling it is cut off.
As the downdrafts and rain cool the land, the
strength of the updraft slows. Without an
______________________, the system will dissipate,
and eventually die out (just like a thunderstorm). This
may take days and 100’s of miles.