Strange Circles, Rings and Geometries on Radar in the USA
Immagine: 25,31 KBAs you know a great deal of speculation and rumors surrounds the subject of cloud
circles. These have been highlighted by radar across the USA and Canada in the
last 18 months or so.
I have made many inquiries within the Meteorological Service in the UK (Dept of
MOD-British Government) and here in the USA through a number of Meteorological
organizations. In the USA it has been impossible to reach an actual human being - all
attempts are either ignored or referred to machines.
I have been successful with detailed and very useful discussion with scientists
working for the British Government. It seems most likely that these strange patterns
are a radar artifact. It has been confirmed by the MOD that the cloud circles are also
appearing in the UK but that they have no reason to believe that they are
meteorological in nature.
For information here is a reply from an expert at the UK Met. office:
Colin,
Your email has been passed onto me for reply.
I have looked at the sample image and my guess would be that this and similar
patterns do not have a meteorological origin. There can be several causes of
geometric ring or spoke patterns:-
a) If there is an unexpected increase in the amount of electrical noise in the radar
system. This noise tends to 'break through' at a particular range because the
effective gain is higher at long range to compensate for the inverse square fall off in
the signal. Having said that, the smaller 'holes' in your sample image at extreme
range dont fit this.
b) when the engineers are checking or calibrating the radar, they may inject artificial
signals into the system but forget to turn off the data supply to the outside world. This
can result in ring patterns.
c) Interference from other radars or noise sources can produce spoke patterns. -
particularly when two radars which are close together in frequency are pointing at
each other.
The UK weather radar network also suffers from similar artifacts to some extent
(maybe one or two incidents per month on average)
Malcolm Kitchen,
Meteorological Office
MOD-UK
http://www.colinandrews.net/OtherCircles.html