The nameless hurricane
- April 2, 2004: Hurricanes are terrifying. They rip trees right out of
the ground, hurl cars into the air, and flatten houses. Their winds
can blow faster than 100 mph. Some hurricanes have been known to pull
a wall of water from the ocean 20 feet high then fling it inland,
inundating miles of coast. No other storms on Earth are so destructive.
Or so memorable. The most powerful hurricanes are talked about for
decades, long after the floods subside and trees grow back. What child
in Mississippi today hasn't heard of Hurricane Camille, the monster
storm that traumatized their parents in 1969? Hurricanes are the only
storms we actually name, like people, to help us remember.
Naming hurricanes also helps prevent confusion. Sometimes there are
two or more of the storms raging at the same time. Weather forecasters
and storm trackers use names like Camille, Hugo and David to clarify
which storm they're talking about. For these reasons, every hurricane
gets a name. Always.
That is, until last week, on March 28th, when a nameless hurricane
crashed into Brazil. The storm made landfall near Torres, a small town
in the state of Santa Catarina about 500 miles south of Rio de Janeiro.
"This really caught everybody off guard," says NASA hurricane
researcher Robbie Hood. "Hurricanes aren't supposed to be in that part
of the world."
Weather satellites have been circling Earth for more than 40 years.
During that time they've spotted hurricanes (also called "typhoons" or
"cyclones") in the northern Atlantic Ocean, and on both sides of the
equator in the Pacific and Indian Oceans, but never before in the
"Vertical wind shears in the south Atlantic are too strong for
hurricanes," Hood explains. Winds in the upper troposphere (about 10
km high) are 20+ mph faster than winds at the ocean surface. This
difference, or shear, rips storms apart before they intensify too much.
A typical hurricane starts out as a cluster of ordinary thunderstorms.
Powered by heat from warm tropical waters and guided by Coriolis
forces, the storms swirl together, joining forces to create a tropical
depression...then a tropical storm...and finally a full-fledged
hurricane. Wind shears in the south Atlantic usually stop this process
at the stage of tropical depression.
There are exceptions. In 1991, for instance, the US National Hurricane
Center documented a tropical storm off the coast of Congo. It lasted
about five days as it drifted toward the central south Atlantic, but
it never reached hurricane strength. (The minimum threshold for a
hurricane is 74 mph winds.)
What was different about the March 2004 storm? Why did it become a
hurricane? No one knows.
When the storm crashed into Brazil, local observers weren't even sure
it was a hurricane. Brazil has no ground-based network of weather
stations to measure wind and rain from tropical storms. "There are no
'Hurricane Hunters' in Brazil," adds Hood. "The storms are so rare."
Space satellites, however, gathered a great deal of data. "NOAA polar
orbiting satellites measured the temperature of the storm's eye," says
climate scientist Roy Spencer of the University of Alabama,
Huntsville. "That told us how fast the winds were moving." It was a
category 1 hurricane, he says, an estimate confirmed by NASA's
wind-measuring QuikScat satellite. In addition, NOAA's GOES satellites
and NASA's Terra and Aqua satellites took pictures of the storm at
microwave, infrared, and visible wavelengths, allowing scientists to
monitor the motions of moisture and heat energy through the storm -
valuable data, indeed.
The TRMM spacecraft, a joint mission of NASA and the Japanese space
agency, flew over the storm several times in the days before landfall,
and it gathered perhaps the most revealing data of all. TRMM, short
for Tropical Rainfall Measuring Mission, carries a precipitation
radar, the only one in space. Beaming down through the clouds, the
radar illuminated spiraling bands of rainfall; false color images of
the storm resemble a pinwheel galaxy! Combining data from the radar
and the spacecraft's microwave imager, researchers can estimate rain
rates throughout the hurricane - from top to bottom, from eye to edge.
"This whole episode highlights the advantages of satellites for
hurricane studies, especially where there are no aircraft standing by
to fly through the storms," says Hood. "Satellites can monitor storms
in all parts of the world."
But a problem remains: what to call them? The World Meteorological
Organization maintains a list of hurricane names for every part of the
world except the south Atlantic. Sadly, the March 28th storm did
damage to remember: 500 homes ruined, fishing boats sunk, at least two
people dead and 1500 more homeless. Brazilians are going to be talking
about the storm for a long time, and wondering about hurricanes to come.
South Atlantic hurricanes need names. Somebody somewhere, probably, is
making a list.
See this link for the pics that go with the story :
Be sure to take a look at this. It is a very large download, but WELL
worth the wait. If you look closely, you can see the ocean swells
associated with the storm. Incredible!