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Hurricanes.
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They’re one of the most deadly and destructive
forces on Earth, causing unfathomable damage,
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uprooting lives and trees alike.
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The storms that come close to land often necessitate
mass evacuations, destroy developments and
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homes, cause flooding and severe weather,
and displace millions of people.
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Particularly severe and destructive hurricanes
remain in public memory for decades, like
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Hurricanes Katrina, Sandy, and Harvey, to
name a few.
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Hurricanes originate in the Atlantic basin,
which consists of the Atlantic Ocean, the
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Caribbean Sea, and the Gulf of Mexico, as
well as in the eastern North Pacific Ocean.
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They can also form in the central North Pacific
Ocean, though formation is less frequent there.
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While hurricanes are fierce, intense storms
that seem like they could pop up anywhere
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and wreak havoc across the entire tropics
in one fell swoop, for some strange reason,
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hurricanes almost never form at the equator.
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In fact, it is extremely rare for them to
form anywhere within a few degrees of the
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equator, with one degree of latitude covering
about 69 miles or 111 kilometers.
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And not only do tropical storms rarely form
at the equator, but hurricanes also almost
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never cross it either.
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So why aren’t there hurricanes at the equator?
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What makes the area around 0 degrees latitude
one of the safest places on Earth from these
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super violent tropical storms?
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How is it possible that hurricanes would not
consistently form or cross this region?
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Let’s get to the bottom of this utterly
bizarre phenomenon.
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The United States and the Caribbean are frequently
hit by violent and destructive hurricanes.
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Over just the last 30 years, these storms
have caused billions of dollars of damage,
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displacement of millions of people, and countless
casualties.
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Also sometimes called typhoons or cyclones,
hurricanes actually fall under the scientific
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name tropical cyclones.
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The hurricane is said to have gotten its name
from the Taino word ‘huricán,’ who was
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the Carib god of evil.
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The Taino people were the indigenous people
of the Caribbean and Florida, which are areas
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historically hit by lots of tropical storms.
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The Carib god was derived from the Mayan god
of wind, storm, and fire, named Huracán.
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When Spanish colonizers passed through the
Caribbean, they adopted the word huracán
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to describe the natural phenomenon we know
today as the hurricane.
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So then why today do we refer to hurricanes
mostly by first names?
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Hurricanes occur on average 12 times a year
in the Atlantic basin, with most typically
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appearing between June 1 and November 30,
which is known as hurricane season.
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Because these storms can last for weeks, and
multiple storms can take place at the same
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time in the same body of water, scientists
have taken to giving the storms names to reduce
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confusion about which storm a forecaster is
referring to when addressing the public.
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In the early 1800s, tropical storms were named
for the Saint’s Day during which it occurred.
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In Australia during the late 1800s, meteorologist
Clement Wragge began giving traditionally
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female names to storms.
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The military meteorologists of the United
States adopted this process in the Pacific
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during World War II, and the US formally adopted
the method in 1953 after first considering
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naming hurricanes with the phonetic alphabet,
with names like Able, Baker, and Charlie.
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In 1978, traditionally male names began to
be implemented too, and today, feminine and
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masculine names are alternated.
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The World Meteorological Organization currently
has a rotating list of six years’ worth
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of names, which repeats names every seven
years.
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Names of storms that cause significant loss
of life or damage to property are retired,
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though, because bringing back such names may
prompt painful and traumatic memories for
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impacted people.
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In other areas, tropical cyclones receive
names unique to the basin in which they exist
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and the regions they affect.
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Names are often borrowed from areas of the
world that the storms affect.
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For instance, in the northwest Pacific near
China, Japan, and the Philippines, tropical
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cyclones often receive names common to Asian
cultures, including names of flowers and trees.
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But what even are hurricanes?
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Tropical cyclones, which include hurricanes,
are rotating low-pressure weather systems
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with organized thunderstorms, but without
fronts.
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A front is a boundary that separates two air
masses with different levels of density.
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Hurricanes tend to form in tropical seas where
the waters are above 26 degrees Celsius.
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This is because tropical cyclones need warm
ocean waters as an energy source,
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background spin, and low vertical wind shear—which
is a measure of the change in wind speed and
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direction with height in the atmosphere—to
form.
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But not all tropical cyclones are hurricanes.
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Tropical cyclones with maximum sustained surface
winds of under 39 miles per hour are called
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tropical depressions, and tend to be less
severe than tropical storms, which have maximum
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sustained winds of 39 miles per hour or higher.
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A tropical cyclone only reaches hurricane
status once it reaches one-minute maximum
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sustained winds of at least 74 miles per hour,
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and it must be over the Atlantic Ocean.
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The intensity and severity of hurricanes is
measured by its maximum sustained wind speed,
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through what is called the Saffir-Simpson
Hurricane Wind Scale, which operates on a
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1 to 5 rating scale.
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These ratings are called categories, which
you’ve probably heard a newscaster use when
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describing a hurricane, often shortening them
to “cat.”
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These categories help describe the hurricane’s
potential for damage, with the higher the
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category, the more likely it is to be destructive.
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So where do they come from?
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Originating in the Atlantic basin, hurricanes
form from the warm, moist air above ocean
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waters near the equator.
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As the warm air rises, it creates a region
of lower air pressure underneath, and nearby
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areas of higher air pressure push into the
area with lower pressure.
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That air then begins to warm and rise as well,
creating another low pressure zone, that more
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air gets pushed into, and so on, repeating
the cycle.
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The air that rises will eventually start to
cool down, and as a result, the water in the
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air forms a group of clouds.
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These clouds will begin to spin from the cycle
of swirling air flowing into the low pressure
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zones, and eventually these spinning clouds
will grow into a cyclone.
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The cyclone is fed by the heat and evaporating
water of the ocean.
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This creates the immense and devastating natural
phenomenon we know as hurricanes.
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Hurricanes are made up of three distinct parts:
the eye, the eyewall, and the rainbands.
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The eye of a hurricane is a round area that
can range from 19-40 miles in diameter.
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You may have heard someone say that they felt
like they were in the eye of a storm before,
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meaning they were calm and peaceful amidst
chaos around them, and this expression aptly
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describes what being in the eye of a hurricane
might be like: a generally peaceful and calm
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area surrounded by high winds, heavy precipitation,
and intense thunderstorms.
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But since a hurricane is moving, your time
in the safety of the eye is limited and soon
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you’ll pass into the eyewall.
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The eyewall of the storm is where the strongest
winds and rains are.
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It is a ring of thunderstorms that surrounds
the eye of the hurricane.
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And then there’s the rainbands of a hurricane,
which are clouds that spin outward, expanding
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the storm to a larger size.
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The intensity of the storm can be measured
through the Saffir-Simpson Wind Scale.
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Storms that reach Category 3, which has a
wind speed of 111 miles per hour or higher,
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are considered major hurricanes.
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These storms are predicted to cause high rates
of property damage, which includes inland
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flooding and electricity shortages.
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But what might be scariest of all about hurricanes,
is that there are more of them than ever before.
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Especially in the past half a century, the
hurricanes we experience have become longer,
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more intense, and more frequent.
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This is especially true in the North Atlantic,
and the frequency of the strongest hurricanes—that
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is, Category 4 and 5 hurricanes, has increased
as well.
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The recent increase in frequency and intensity
of tropical storms is partly linked to higher
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sea surface temperatures in the region where
Atlantic hurricanes form and move through.
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And studies predict that these trends will
continue as the climate continues to grow
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warmer due to climate change, as hurricane
intensity and rainfall escalate.
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Hurricanes have long been one of the deadliest
forces of nature, so the fact that they are
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getting more powerful is terrifying.
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Over a century ago, as early as 1893, the
Cheniere Caminada Hurricane was a powerful
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Category 4 hurricane that made landfall on
the small island of Cheniere Caminada, Louisiana,
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which had wind speeds of over 130 miles per
hour.
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A storm surge of nearly 18 feet decimated
the small fishing community, leaving only
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a few homes intact and killing over 770 of
the town’s 1,471 community members.
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For reference, a storm surge is the rise in
sea level that is solely caused by a storm.
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As the hurricane traveled over the Mississippi
delta into southern Mississippi and Alabama,
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an estimated 2,000 people were killed.
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Clearly, the Cheniere Caminada hurricane was
deadly, destructive, and relentless.
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In 1900, the Galveston Hurricane, a Category
4 hurricane that hit the island city of Galveston,
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Texas, became one of the deadliest natural
disasters in United States history.
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The high storm tides of up to 15 feet inundated
the island, much of Texas’ coast, and caused
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about 8,000 deaths, cost $30 million in damage,
and left 10,000 residents unhoused as a result
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of so many buildings being damaged.
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Other notable storms of the early twentieth
century include the San-Felipe Okeechobee
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Hurricane of 1928 and the Great Labor Day
Hurricane of 1935.
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Additionally, Hurricane Camille, which took
place in 1969, was one of just four Category
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5 hurricanes to ever make landfall in the
continental United States since the start
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of the century.
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Hurricane Camille reached the Mississippi
Gulf Coast and destroyed the wind-recording
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instruments of the area, so top maximum sustained
wind speeds are unknown.
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The storm brought a storm tide of over 24
feet, resulting in 256 deaths and costing
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over $1.4 billion in damage.
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But perhaps the most severe in recent memory
was Hurricane Katrina, which lasted for nine
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days in August 2005 and caused 100 billion
dollars in damage.
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Hurricane Katrina was the costliest hurricane
in United States history and was one of the
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top five deadliest hurricanes the United States
has ever seen.
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The hurricane originated over the Bahamas,
moved westward toward Florida, and made landfall
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there two days after forming.
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Hurricane Katrina then tore through the Gulf
of Mexico, growing larger and stronger, before
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again making landfall in southeast Louisiana.
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Hurricane Katrina was registered as a Category
5 hurricane at its peak in the Gulf of Mexico,
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but was downgraded to a Category 3 hurricane
when it reached Louisiana.
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The devastation from the hurricane was incredible,
with at least 1,245 people dying during the
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hurricane and from the floods it caused.
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In the Greater New Orleans area, two-thirds
of the flooding was due to levee and floodwall
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failure, as the storm surge caused 52 breaches
in the levee system leading to mass flooding.
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Hurricane Katrina caused thousands to be displaced
from their homes and forced to find shelter
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in poor, makeshift housing like the Superdome.
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In sum, Hurricane Katrina caused an estimated
four times the amount of damage that Hurricane
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Andew caused in 1992.
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One of the most brutal, widespread and recent
hurricanes that impacted the United States
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and Caribbean was Hurricane Sandy in 2012.
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Hurricane Sandy lasted for twelve days in
late October and early November of 2012.
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In the United States alone, the hurricane
had a wide-ranging impact, affecting the entire
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eastern seaboard
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from Florida to Maine, totalling 24 states.
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The tropical storm developed from a tropical
wave in the west Caribbean and intensified
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to hurricane status before making landfall
near Jamaica and then Cuba.
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After that, the hurricane traveled up along
the eastern coast of the continental United
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States, reaching all the way to New Jersey
with hurricane-force winds.
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Hurricane Sandy peaked as a Category 3 storm
near Cuba before decreasing intensity to a
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Category 1 hurricane when it hit the U.S.,
but despite its low rating, the storm had
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widespread, deadly, and destructive impacts.
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In New York City, a storm surge caused the
city’s streets, tunnels, and subway lines
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to flood.
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As a result, areas within and around the city
lost power, and financial markets in the area
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closed.
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In New York, 71 people died as a result of
Hurricane Sandy, and 233 people died total.
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For those twelve days, much of the eastern
United States was in a state of emergency,
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with many people living without power and
electricity for the weeks it took to repair.
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The impacts of the hurricane extended all
the way to the Midwest, reaching Michigan
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and Wisconsin, which experienced gale-force
winds and high waves from Lake Michigan.
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Altogether, the intensive damage caused by
Hurricane Sandy cost $75 billion.
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Other notable hurricanes in recent years include
Hurricane Ike in 2008, which hit Cuba and
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Texas and caused $37.5 billion in damage;
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Hurricane Wilma of 2005, which went down in
history as the most intense tropical cyclone
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ever recorded in the Atlantic Basin in the
same year that Hurricanes Katrina and Rita
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had already hit;
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and Hurricane Andrew, which—when it struck
the Bahamas, South Florida, the Gulf of Mexico,
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and Louisiana in 1992—was the most destructive
hurricane in American history.
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When adjusted for inflation, Hurricane Andrew
remains the third most costly hurricane in
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history, destroying 63,000 homes and damaging
another 101,000, causing $500 million in damage
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to oil companies, and catalyzing at least
28 tornadoes on the Gulf Coast.
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When all is said and done, hurricanes seem
to be getting stronger, more intense, and
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are beginning to cause more and more damage.
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Hurricanes clearly are relentless, unstoppable,
and unforgiving storms that wreak havoc throughout
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the Atlantic basin.
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You might assume that the deeper into the
tropics you go, the more likely it is to come
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across a tropical cyclone.
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However, the equator just might be one of
the safest places in the world in terms of
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hurricane risk.
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Although the equator is warm and tropical,
hurricanes rarely form within 300 kilometers
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(or about 186 miles) of the equator.
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So what’s the deal?
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Why don’t you find earthquakes at the equator?
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It partially has to do with the coriolis effect.
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Hurricanes that form south of the equator
spin clockwise, while storms formed north
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of the equator spin counterclockwise.
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This is caused by the Earth’s spin, which
causes the air to be pulled clockwise or counterclockwise
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in the Northern and Southern hemispheres respectively.
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At the equator, even when the air is calm,
the Earth and the atmosphere are actually
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moving at over 1,000 miles per hour, which
follows the direction of the Earth’s spin
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from west to east.
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At the equator, the Earth’s circumference
is largest, so something on the equator technically
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moves faster than something that is situated
away from the equator.
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In other words, anything on the equator travels
a greater distance in the same time, when
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compared with anything located north or south
of the equator on the Earth’s surface.
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When air moves north or south from the equator,
it will still also travel quickly eastward
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or westward respectively, at least compared
to its new surroundings.
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This means that air flowing north from the
equator will evidently stray to the right,
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while air traveling south from the equator
will seem to move to the left.
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This is what scientists call the Coriolis
effect, which is what causes patches of stormy
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weather to essentially ‘spin up’ into
a hurricane.
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More specifically, the Coriolis effect is
a force that acts on our atmosphere as a result
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of the Earth rotating faster at the equator
than at the poles.
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As a result, air currents and storms bend
to the right in the northern hemisphere and
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the left in the southern hemisphere.
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The degree to which storms bend is impacted
by air speed and the size of the storm system.
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The magnitude of the Coriolis effect is weak
near the equator and gets increasingly stronger
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around the Earth’s poles.
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Hurricanes feed on their environment to increase
their speed and energy, collecting rotation
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from their environment.
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Because hurricanes need warm waters for energy,
low vertical wind shear, and some background
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spin to form, it is not feasible for the storms
to form near the equator, where the Coriolis
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effect is weak.
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Though the waters are balmy and warm and the
shear is low at the equator, the weak Coriolis
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effect there means there is not enough background
spin to cause thunderstorms to form into tropical
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cyclones.
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But if hurricanes are unable to form at the
equator, what’s stopping them from moving
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across the equator once they do form elsewhere?
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What leads to this band of relative hurricane
safety around the globe?
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The reason hurricanes don’t cross the equator
has to do with the fact that the spin of hurricanes
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is counterclockwise north of the equator and
clockwise south of the equator.
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Because of this, the storm would effectively
have to stop spinning, reverse direction,
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and spin in the other direction to continue
across the equator.
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As the hurricane begins to ingest air rotating
in the opposite direction, it would most likely
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weaken and collapse.
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The Coriolis effect causes storms to move
away from the equator due to what is called
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beta drift.
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The force pushes storms to the north and west
in the Northern Hemisphere, and to the southeast
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in the Southern hemisphere.
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Because the tropics lack large-scale weather
patterns, such as a cold front, that might
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counteract this motion, tropical cyclones
are never pushed across the equator.
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In theory, a hurricane could possibly cross
the equator if it was ‘the perfect storm.’
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According to one professor of meteorology
at the University of Hawaii, a well-developed
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storm could potentially be strong enough to
continue its momentum over the relatively
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weak Coriolis force and reach the equator,
but it is highly unlikely and would take perfect
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conditions to accomplish.
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As a result, a hurricane crossing the equator
is a phenomenon that has never been observed
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happening in the real world.
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Though hurricanes rarely form within roughly
186 miles of the equator, there are cases
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in which the improbable became reality.
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In fact, in 2001, Typhoon Vamei did just that.
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The typhoon was seen spinning about 93 miles
north of the equator, but scientists say that
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this is a rare exception that happens less
than once in a century.
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Scientists believe that winds interacting
with the island terrain of the Indonesian
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archipelago may have contributed to such rapid
rotation that Tropical Cyclone Vamei was able
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to approach the equator.
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Scientists suggest that even if it were possible
for a storm to cross the equator, it wouldn’t
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last long in any case.
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It is conceivable that a storm could cross
the equator for a short distance, since around
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the equator, there is fairly small opposing
rotation.
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However, according to researchers, it is unlikely
or perhaps even impossible for a tropical
00:20:20
cyclone to cross several degrees of latitude
into the opposite hemisphere.
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Ultimately, the likelihood of a storm ever
crossing the equator seems to be next to none,
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given the competing factors associated with
the Coriolis effect.
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However, as climate change escalates and tropical
storms become more frequent, more severe,
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and more unpredictable, it’s looking more
and more likely that perhaps the perfect storm
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could eventually arise.
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And if it does, it might be one of the deadliest
of all time.
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One potential game-changer for this phenomenon
lies in the fact that as climate change escalates,
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storms in the northern and southern hemispheres
are predicted to get stronger, more intense,
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and more destructive.
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There is increasing precipitation associated
with storms in more recent years, which is
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expected to continue in the future.
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The storm surges associated with these storms
are also anticipated to increase with climate
00:21:16
change.
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These changes within tropical storms are associated
with increased ocean and air temperatures,
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as well as sea level rise caused by melting
glaciers and sea ice.
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Scientists report that climate change is increasing
the upper limit on hurricane strength and
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precipitation rates, given increasing temperatures
of the ocean and atmosphere, providing for
00:21:38
more energy to the storm and more intense
rain respectively, and it is expected that
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hurricanes will result in more damage to infrastructure,
property, and human and animal life in the
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years to come.
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Though climate change does not impact the
rotation of the Earth and thus will not directly
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impact the chances of a hurricane crossing
the equator, the phenomenon is associated
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with increasingly severe and frequent storms,
which means there is a higher likelihood of
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a rare storm at a low latitude being able
to achieve higher intensity and moving toward
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the equatorial region.
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In perfect conditions, such a storm may be
able to better maintain there, as climate
00:22:18
change increases the strength of the strongest
storms.
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But the Coriolis effect makes it highly unlikely
for hurricanes to form near or cross the equator,
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and as a result, the equator and its surroundings
is a virtually hurricane-free zone.
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Areas like Ecuador, Colombia, Indonesia, northern
Brazil, Gabon, São Tomé and Príncipe, Gabon,
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and parts of Kenya and Somalia may all be
some of the coastal areas that are safest
00:22:44
from the impacts of hurricanes.
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At the same time, storms that follow a trajectory
toward the equator also likely will weaken
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and collapse due to the Coriolis effect.
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In some cases, the lack of spin and minimal
time to develop while approaching the equator
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may be irreversibly catastrophic for these
tropical storms.
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In a world where tropical storms and especially
hurricanes are increasing in intensity and
00:23:11
sometimes frequency, the Coriolis effect is
one of the few predictable forces that counters
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the sporadic, violent, and relentless storms
that so often destroy infrastructure and uproot
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human lives.
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By late this century, hurricane models predict,
on average, that there will be a slight decrease
00:23:29
in frequency of total annual tropical cyclones
but that the strongest—Category 4 and 5
00:23:34
hurricanes—will grow to be more common.
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here is some uncertainty to whether this will
definitely take place, but scientists believe
00:23:41
that this trend represents the most likely
outcome.
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At the same time, models almost unanimously
predict that hurricane precipitation will
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increase as the Earth’s average temperatures
rise.
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This is all due to climate change, which is
one of the factors that will most directly
00:23:58
impact the creation, frequency, and intensity
of hurricanes.
00:24:03
With increasingly powerful and more frequent
severe hurricanes, the likelihood of a so-called
00:24:08
perfect storm increases.
00:24:10
Though extremely unlikely, hurricanes near
the equator could appear in the future, although
00:24:15
it seems unlikely that one will ever cross
it.
00:24:18
Hurricanes destroy lives, property, and infrastructure,
costing billions of dollars of damage and
00:24:24
displacing thousands of people.
00:24:26
Despite their unrelenting and destructive
ways, it’s quite remarkable that the powerful
00:24:30
storms are rendered weak and unstable when
in proximity to the Earth’s equator.
00:24:35
The Coriolis effect, which impacts the spin
of tropical storms and the planet alike, is
00:24:41
a force to be reckoned with, to say the least.
