It
looks like rain but it’s actually secret military exercises
What
looked liked rain on an Aussie weather radar this week turned out to
be masking something a lot more powerful
A Romanian helicopter deploys chaff during a Romanian Navy Day. Picture: Jonathan NelsonSource:Flickr
7
February, 2019
If
you checked the weather radars for Sydney yesterday you could have
been forgiven for expecting a patch of heavy rain just north of the
city. But if you poked your head out the window, it was nothing but
blue skies.'
What
appeared to be an ominous storm cloud rolling across the weather
radar was actually a military aircraft tactic used to hide activity
and confuse the enemy.
Known
as chaff, it’s a radar countermeasure in which aircraft or other
military targets spread a cloud of small, thin pieces of aluminium,
metallised glass fibre or plastic. The radar-jamming material either
appears as a cluster of targets on radar screens or overwhelms the
screen with hundreds of returns, or “false echoes”.
ABC
weatherman Graham Creed explained the phenomena to listeners
in Sydney yesterday
evening, telling residents not to worry about the threat of any
rainfall.
“If
anyone out there’s been looking at the Sydney radar, what you can
see those echoes moving towards the northern suburbs of Sydney, it’s
not actually rainfall,” he said.
“It’s
the Williamtown RAAF base and they’re putting what’s known as
chaff in the atmosphere.”
The
reported reason for deploying the chaff was to shield the activity of
Australian fighter jets from any potential prying eyes during a
training exercise.
“The
idea of it is that it hides what they’re doing underneath it,” Mr
Creed explained. “They’re doing manoeuvres with their aircraft.
They drop this chaff and it spreads out and then it creates an echo
so you can’t see individual movements.”
The
air force base is just north of Newcastle but the chaff material
began floating south across northern Sydney.
The
radar countermeasure was developed independently by the German, the
UK, US and Japanese militaries around the time of the World War II.
Still to this day most military aircraft and warships have chaff
dispensing systems for self-defence.
“It’s
a pretty old technology now,” says Dr Jean Bou from the ANU
strategic and defence studies centre.
“It’s
basically a way to confuse radar. In its original guise … it was
basically strips of aluminium foil and it was thrown out of aircraft
in the second world war to confuse enemy radar,” he said.
“Radar
reflects off it and gets a bounce. Instead of seeing individual dots
and a whole bunch of aircraft on the radar it just sees this wall of
radar reflection coming back, so it’s difficult to identify
targets.”
A
spokesperson from the Australian Department of Defence said chaff was
used as part of a “routine fighter jet aircrew” training
exercise.
“The
use of chaff during training evolutions is a regular occurrence and
is governed by strict safety procedures for both Australian Defence
Force personnel and the public.”
The
chaff that was released was made up of “aluminium fibres thinner
than a human hair which are tightly wound together and then dispersed
by the wind when released,” the spokesperson said.
While
it’s designed to confuse the enemy, given the fact that chaff can
appear red on weather radars (the same colour as dark, rain producing
storm clouds), it can also temporarily confuse meteorologists.
That
happened in December when large
blips appeared on weather radar over the US states of Illinois and
western Kentucky,
which the National Weather Service described as “interesting”
before the source was revealed to be a military operation.
Despite
concerns from public health and environmental bodies over the years
that the materials used in chaff can cause harm, there doesn't appear
to be a great deal of public research on the matter.
In
a 1998 review of research sponsored by the US Department of Defence
regarding the environmental effects of chaff, researchers said the
“widespread environmental, human and agricultural impacts of chaff
as currently used in training are negligible and far less than those
from other man-made emissions.”
In America...
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