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Re: (meteorobs) Noctilucent Clouds (fwd)



One for you to answer?

---------- Forwarded message ----------
Date: Wed, 9 Jul 1997 21:41:30 -0400
From: Thomas Ashcraft <72632.1427@compuserve.com>
To: "INTERNET:meteorobs@latrade.com" <meteorobs@latrade.com>
Subject: Re: (meteorobs) Noctilucent Clouds

Steve H. wrote:  >>>... I wonder whether there is a connection between
E-layer radio-reflectivity and the clouds?<<<



I have often wondered about a possible correspondence between noctilucent
clouds and sporadic-E radio phenomena. Does anyone know if radio meteor
observers, sporadic-E monitors ( known as radio DX'ers ), and NLC observers
have ever compared data? 

I wonder if there is a periodic comet related meteor dust quality that is
under the threshold of incandescence so that a meteoric particle would
neither be visually detectable nor reflective of individual radio scatter
bursts. 

I wonder if there are certain cometary meteor showers ( as yet to be
discovered? ) that are made up of particles so fine that they are not
detectable as "normal" meteor showers but in fact cause a distinct infusion
of dust into the ionosphere resulting in sporadic-E and NLC. 

Has this topic been studied well?

Clear skies,
Tom Ashcraft
Santa Fe, New Mexico


Yes, this suggestion has been made many times. I myself looked into this; the 
heights of both are accurately known, and the nc's occur significantly lower
than the Es layers; time of observation is different; and as far as I know,
there
has been no correlation between days when nc's have been observed and extreme 
excursions of Es happened.

Incidentally, Es occurs on the HF and lower VHF bands very frequently in the
summer months; its excursions producing a critical frequency above 100 MHz are
however much rarer in this part of the world.

For further information on Es and its theories, including my views on its
connection
with meteors, all based on scientific observations and some of my own work,I
suggest 
you read "The VHF/UHF DX Book", ed. I. F. White, ISBN 0 9520468 0 6, Chapter 2 
"VHF/UHF Propagation" by Dr G.H. Grayer G3NAQ/AE4PI; published for the Radio
Society
of Great Britain and also obtainable from the American Radio Relay League.



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