[meteorite-list] Scientists Puzzle Over Ice From Sky in New Zealand

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:32:11 2004
Message-ID: <200401301716.JAA11703_at_zagami.jpl.nasa.gov>

http://www.nzherald.co.nz/storydisplay.cfm?storyID=3546593

Scientists puzzle over ice from sky
By STUART DYE
The New Zealand Herald
January 31, 2004

When a mysterious ball of ice crashed through Jan Robertson's
house, the 80-year-old had no idea she would plunge New
Zealand into the centre of a scientific frenzy.

Geochemists, astrophysicists, meteorologists and geologists in
Brazil, China, Spain and Russia believe the intrusion may have
been New Zealand's first "megacryometeor".

To the layman that is hailstones - jumbo hailstones.

Early investigations by the Civil Aviation Authority suggest that
the ice contained chlorine, an indication that it had been treated
by man.

"We understand there were two flights over the area at the time
and it's possible a leak in an aircraft water pipe caused the
block," said CAA spokesman Bill Sommer.

However, inspections of both aircraft have revealed no signs of
where the ice could have come from.

Mrs Robertson got used to phone calls from scientists around
the world but yesterday, 10 days after the incident, she said
things had quietened down.

She was cleaning her Meadowbank home and her husband,
Bruce, was in the garden when the ice missile the size of a rugby
ball, travelling at about 400km/h, hurtled through the kitchen roof.

The International Working Group Fall of Blocks of Ice
(IWGFBI) is a fledgling team of renowned scientists dedicated
to investigating megacryometeors.

There have been 50 documented cases around the world. Ice
balls have punched holes in roofs, smashed car windshields and
whizzed past people's heads.

The group's founder, Jesus Martinez-Frias, a planetary
geologist, began investigating the ice falls after a spate in Spain
three years ago.

It started with a soccer-ball-sized chunk plummeting from the
sky on a sunny Madrid day and smashing through a parked car.

In something resembling a biblical plague, pieces of ice weighing
up to 3kg rained on Spain out of cloudless skies for 10 days, then
the phenomenon ended as suddenly as it began.

At first, scientists thought the giant hail was unique to Spain.
But they have accumulated evidence that megacryometeors are a
global event and have documented ice balls falling from cloudless
skies everywhere from China to the United States.

They believe the 50 confirmed falls are a fraction of the actual
number - most may hit unoccupied areas or melt before
discovery.

The average weight is 12 to 15kg, but one whopper in Brazil
tipped the scales at 200kg - the size of a V8 car engine.

Alarming as this may be for people's homes, cars and health, the
scientists have a different concern.

"I'm not worried that a block of ice may fall on your head," said
Professor Martinez-Frias, speaking from Madrid. "I'm worried
that great blocks of ice are forming where they shouldn't exist."

His team quickly ruled out obvious explanations.

The ice balls, for instance, were not frozen water from toilets
flushed on jetliners - they lacked urine or disinfectant traces.

They could not be debris from a comet as lab tests showed that
megacryometeors had the distinctive chemical signature of ice in
ordinary terrestrial hailstones.

That leaves monster hailstones forming in a cloudless sky - a
notion that defies more than a century of research on hail
formation.

Scientists are concentrating on two possibilities. One, that
megacryometeors are a weird byproduct of global warming; two,
that ice crystals in aircraft contrails left floating in the air for days
are swept through cold, humid air pockets, forming large balls.

Neither theory is particularly popular.

"I don't like to claim that anything is impossible, but this comes
awfully close," says Charles Knight, a hail expert at the
University Corporation for Atmospheric Research in Colorado.

The worry is that, if megacryometeors are a result of global
warming, they are likely to increase.

Professor Martinez and his colleagues are pooling their
knowledge, but an answer is likely to take years.

How hail forms

* Hail forms in the updrafts and downdrafts of thunderstorms.

* Freezing particles join as they are tossed round in the wind
and the hailstone grows, layer by layer.

* Megacryometeors show the telltale onion skin layering seen in
hailstones.

* They also contain dust particles and air pockets found in hail.

* But they are formed in cloudless skies, a notion that defies
research on hail formation.
Received on Fri 30 Jan 2004 12:16:55 PM PST