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Flashcards in Hurricanes and Severe Weather Deck (44)
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What are Tropical Cyclones?

Cyclones are large low pressure centers, with numerous thunderstorms, heavy rainfall and winds


Where do Tropical Cyclones get their energy from?

They get their energy from the release of latent heat (from evap) during condensation, occurs over warm tropical oceans


When do Tropical Cyclones form in North Atlantic and why then?

Late summer, early fall; warmest water temps


Where do all Tropical Cyclones originate?

All Tropical cyclones originate in tropics.


Where do North Atlantic tropical storms begin?

All Tropical cyclones originate in tropics. North Atlantic tropical storms begin off the coast of Africa


What is the growth cycle of North Atlantic Hurricanes?

1. Tropical wave (low pressure off coast of africa)
2. Tropical disturbance
3. Tropical depression (74 mph winds. It has an eye)


What is a hurricane?

A hurricane is a tropical storm with wind speeds that have reached a constant of 74 miles per hour or more.


What are the different categories of hurricanes according to the Saffir/ Simpson Hurricane Scale?

Category 1 - winds: 74-95mph.
Category 2 - winds: 96-110mph
Category 3 - winds: 111-130mph
Category 4 - winds: 131-155mph
Category 5 - winds: 156+ mph


Strong tropical storms are called Hurricanes, Cyclones, and Typhoons depending on where you are in world. Where in the world are they called these?

North America, Central America - Hurricanes

East Coast of Africa, Madagascar, Australia - Cyclones

Southeast Asia, India, China, Japan, Korea - Typhoons


What are the patterns of precipitation in a tropical cyclone?

Look at page 10!


What does the eye of a hurricane have?

The eye has sinking air and calm conditions! (higher pressure)


What are the strongest winds in a hurricane (other than the eye)?

The top right side of a hurricane has the strongest winds.


What are the major risks associated w/ hurricanes?

•High winds
•Heavy rainfall
•Storm surge
•Rip tides


Which of the major risks associated with hurricane cases the most deaths?

Storm surge is the cause of about 90% of hurricane deaths!


What do high winds do to water in hurricanes?

High winds causes the water to pile up higher than the ordinary sea level


What is the most deadly natural disaster in the US? How many deaths?

Hurricane of 1900, Galveston, TX. Deaths 6000–8000!


What do hurricanes do to coastal landscapes?

Change landscapes dramatically


What happened to Harreras Island, NC, September 20, 2003?

Hurricane Isabel slammed into the Outer Banks of North Carolina washing out NC Highway 12 and breaching the island.


Why are there no hurricanes at the equator?



Why so many cyclones in western Pacific?



Why are there no tropical cyclones in SW Pacific and SW Atlantic?



What is the first recorded South Atlantic Hurricane?

Hurricane Catarina (2004)


How many thunderstorms occur every day around the globe?

At any given time >2000 thunderstorms are occurring around the globe


What are the key ingredients to produce a thunderstorm?

1.Warm, moist air near surface
2.A lifting mechanism, often convection or frontal: given an initial push, air will continue to rise


What is an updraft?



What is a downdraft?



What causes hail formation?

Strong updraft goes to an area with many supercooled water droplets. This causes the growth of hailstones. A downdraft then causes the hail to precipitate.


What is lightning?

Lightning is an atmospheric discharge of electricity, which typically occurs during thunderstorms, and sometimes during volcanic eruptions or dust storms.


Where does 90% of lightning strikes occur? Why?

90% of all lightning strikes occur over land due to enhanced convection


What is thunder? Where is virtually unknown at?

The sudden increase in pressure and temperature from lightning produces rapid expansion of the air surrounding and within a bolt of lightning creates a sonic shock wave.

Thunderstorms are virtually unknown at high latitudes >60º


Where are thunderstorms most prevalent in the US??

The midwest


What are supercells?

Supercell: large storms with strong rotating updrafts, which often burst into stratosphere


How do supercells form?

Slide 26


Where do most tornadoes originate?

Most tornadoes originate from the base of a thunderhead


What is a tornado?

A tornado is a violently rotating column of air in contact with and extending between a cloud (often a thunderstorm cloud) and the surface of the earth.


How are tornadoes measured in the Enhanced Fujita Tornado Intensity Scale?

Based on observed damage NOT wind speed (are estimates!)


What are the levels of the Enhanced Fujita Scale?

Slide 28


What percent of tornadoes fall into the 166-200+ mph range?

Less than 1%


What states have the highest geography of Tornadoes?

Midwest (Look at slide 30)


What percent of tornadoes are found in North America? Why?

N. Am has 90% of all tornadoes. This is due to uninhibited interaction of air masses! cP and mT available&No E-W mountains to stop clash!


Which month has the most tornadoes?

May. June is a close second


What are some examples of tornadoes?

Waterspouts, dustdevils, microburst


What are Waterspouts?

Small Tornadoes over water: Waterspouts are favored by high temps, high humidity, and still air


What are microbursts?

Microburst–Destructive “straight-line”winds up to 160 mph related to thunderstorm downdrafts. Lasts only few minutes. Deadly to small aircraft. Strong downdraft hits ground and spreads out at high speeds (<2 mi, larger are macrobursts)