[Phys-L] Re: Light from fireball visible?

[Brian Whatcott <betwys1@SBCGLOBAL.NET>]

> > At 09:43  -0800 2/8/06, Bernard Cleyet wrote:
> >
> >
> > > A friend asks if the Nagasaki was visible, as reported in "The Empire of
> > > the Sun".
> ////
> > > Was the author using lit. license?
> ///
> Is on the west coast, middle of the island.  In the direction to
> Shanghai, the highest part of the mountain ridge (SW of city) is 1500
> ft   (GOOGLE Earth).
///
> > <>Could the glow be seen from 800 km? I doubt it.
> > There are no reports of the glow of Trinity being seen from that
> > distance, and it was about the same yield as Nagasaki, and also
> > nestled among surrounding mountains.
>
>
> This was my conclusion, also.  Tho the ball had 100 X luminosity of
> sun.  [Aside: To equal the sun, necessarily viewed from  high altitude,
> one would need be 10 times distant from the ball when it subtends one
> half degree.  I obtain ~ 3 k miles.]  From Shanghai  visibility would
> depend on ideal Mie and Rayleigh scattering.


Noctilucent clouds occur at heights of 85km.
They are best seen when the Sun is a few degrees below the horizon.

An intense light source might (possibly?) illuminate such high ice clouds
so that the flash would be visible at places 100's of miles distant; places
where sunrise has yet to take place.



Brian Whatcott    Altus OK    Eureka!
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