2. A tornado is a violent, rotating column
of air which is in contact with both the
surface of the earth and a cumulonimbus
cloud or, in rare cases, the base of a
cumulus cloud. The most intense of all
atmospheric phenomena, tornadoes
come in many shapes and sizes but are
typically in the form of a visible
condensation funnel, whose narrow end
touches the earth and is often encircled
by a cloud of debris and dust. Most
tornadoes have wind speeds between 40
mph (64 km/h) and 110 mph (177 km/h),
are approximately 250 feet (75 m) across,
and travel a few miles (several
kilometers) before dissipating. The most
extreme can attain wind speeds of more
than 300 mph (480 km/h), stretch more
than a mile (1.6 km) across, and stay on
the ground for dozens of miles (more
than 100 km).

3. Tornadoes often begin as funnel clouds with no associated strong winds at the surface, though
not all evolve into a tornado. However, many tornadoes are preceded by a funnel cloud. Most
tornadoes produce strong winds at the surface while the visible funnel is still above the ground,
so it is difficult to discern the difference between a funnel cloud and a tornado from a distance.
Occasionally, a single storm will produce more than one tornado, either simultaneously or in
succession. Multiple tornadoes produced by the same storm cell are referred to as a "tornado
family".Several tornadoes are sometimes spawned from the same large-scale storm system. If
there is no break in activity, this is considered a tornado outbreak, although there are various
definitions. A period of several successive days with tornado outbreaks in the same general area
(spawned by multiple weather systems) is a tornado outbreak sequence, occasionally called an
extended tornado outbreak.
A wedge tornado, nearly a mile wide. This tornado hit Binger, Oklahoma.
Most tornadoes take on the appearance of a narrow funnel, a few hundred yards (meters)
across, with a small cloud of debris near the ground. Tornadoes may be obscured completely by
rain or dust. These tornadoes are especially dangerous, as even experienced meteorologists
might not spot them. Tornadoes can appear in many shapes and sizes.
Small, relatively weak landspouts may only be visible as a small swirl of dust on the ground.
Although the condensation funnel may not extend all the way to the ground, if associated
surface winds are greater than 40 mph (64 km/h), the circulation is considered a tornado. A
tornado with a nearly cylindrical profile and relative low height is sometimes referred to as a
"stovepipe" tornado. Large single-vortex tornadoes can look like large wedges stuck into the
ground, and so are known as "wedge tornadoes" or "wedges". The "stovepipe" classification is
also used for this type of tornado, if it otherwise fits that profile. A wedge can be so wide that it
appears to be a block of dark clouds, wider than the distance from the cloud base to the
ground. Even experienced storm observers may not be able to tell the difference between a lowhanging cloud and a wedge tornado from a distance. Many, but not all major tornadoes are
wedges.

4. The most extreme tornado in recorded history
was the Tri-State Tornado, which roared
through parts of Missouri, Illinois, and Indiana
on March 18, 1925. It was likely an F5, though
tornadoes were not ranked on any scale in that
era. It holds records for longest path length
(219 miles, 352 km), longest duration (about 3.5
hours), and fastest forward speed for a
significant tornado (73 mph, 117 km/h)
anywhere on Earth. In addition, it is the
deadliest single tornado in United States
history (695 dead). The tornado was also the
second costliest tornado in history at the time,
but in the years since has been surpassed by
several others if population changes over time
are not considered. When costs are normalized
for wealth and inflation, it ranks third today.
[90] The deadliest tornado in world history was
the Daultipur-Salturia Tornado in Bangladesh
on April 26, 1989, which killed approximately
1300 people. Bangladesh has had at least 19
tornadoes in its history kill more than 100
people, almost half of the total in the rest of the
world.

6. Hurricane Katrina of the 2005 Atlantic hurricane
season was the costliest hurricane, as well as one
of the five deadliest, in the history of the United
States. Among recorded Atlantic hurricanes, it was
the sixth strongest overall.
Hurricane Katrina formed over the Bahamas on
August 23, 2005 and crossed southern Florida as a
moderate Category 1 hurricane, causing some
deaths and flooding there before strengthening
rapidly in the Gulf of Mexico. The storm weakened
before making its second landfall as a Category 3
storm on the morning of Monday, August 29 in
southeast Louisiana. It caused severe destruction
along the Gulf coast from central Florida to Texas,
much of it due to the storm surge. The most
severe loss of life occurred in New Orleans,
Louisiana, which flooded as the levee system
catastrophically failed, in many cases hours after
the storm had moved inland. Eventually 80% of
the city and large tracts of neighboring parishes
became flooded, and the floodwaters lingered for
weeks. However, the worst property damage
occurred in coastal areas, such as all Mississippi
beachfront towns, which were flooded over 90% in
hours, as boats and casino barges rammed
buildings, pushing cars and houses inland, with
waters reaching 6–12 miles (10–19 km) from the
beach.

7. At least 1,836 people lost their lives in the actual
hurricane and in the subsequent floods, making it
the deadliest U.S. hurricane since the 1928
Okeechobee hurricane. Hurricane Katrina in 2005
was the largest natural disaster in the history of the
United States. Total damage was $81 billion (2005
USD), nearly triple the damage wrought by
Hurricane Andrew in 1992.
Katrina redistributed over one million people from
the central Gulf coast elsewhere across the United
States, which became the largest diaspora in the
history of the United States. Houston, Texas, had
an increase of 35,000 people; Mobile, Alabama,
gained over 24,000; Baton Rouge, Louisiana, over
15,000; and Hammond, Louisiana received over
10,000, nearly doubling its size. Chicago received
over 6,000 people, the most of any non-southern
city. By late January, 2006, about 200,000 people
were once again living in New Orleans, less than
half of the pre-storm population. By July 1, 2006,
when new population estimates were calculated by
the U.S. Census Bureau, the state of Louisiana
showed a population decline of 219,563, or 4.87%.
Additionally, some insurance companies have
stopped insuring homeowners in the area because
of the high costs from Hurricanes Katrina and Rita,
or have raised homeowners' insurance premiums
to cover their risk.

8. All three coastal counties of the state were
severely affected by the storm. Katrina's surge
was the most extensive, as well as the highest,
in the documented history of the United
States; large portions of both Hancock,
Harrison, and Jackson Counties were
inundated by the storm surge, in all three
cases affecting most of the populated areas.
Surge covered almost the entire lower half of
Hancock County, destroying the coastal
communities of Clermont Harbor and
Waveland, much of Bay St. Louis, and flowed
up the Jourdan River, flooding Diamondhead
and Kiln. In Harrison County,
Pass Christian was completely inundated, along with a narrow strip of land to the east
along the coast, which includes the cities of Long Beach and Gulfport; the flooding was
more extensive in communities such as D'Iberville, which borders Back Bay. Biloxi, on a
peninsula between the Back Bay and the coast, was particularly hard hit, especially the
low-lying Point Cadet area. In Jackson County, storm surge flowed up the wide river
estuary, with the combined surge and freshwater flooding cutting the county in half. Remarkably,
over 90% of Pascagoula, the easternmost coastal city in Mississippi, and about 75 miles (121 km) east
of Katrina's landfall near the Louisiana-Mississippi border, was flooded from surge at the height of
the storm. Other large Jackson County neighborhoods such as Porteaux Bay and Gulf Hills were
severely damaged with large portions being completely destroyed, and St. Martin was hard hit;
Ocean Springs, Moss Point, Gautier, and Escatawpa also suffered major surge damage.