Re: model vs observation - getting up to speed
Posted by GES on 2012-04-04 12:26:01
in reply to model vs observation - getting up to speed posted by Steve P. on 2012-04-04 09:40:26
Both sides of the leader produce several different results.
Seen from the illuminated side (sun 'behind' viewer, the first result is a reflection (5%) off a convex 'mirror' which comes back at the viewer (green) widely dispersed in angle so parts of it are seen from all angles. Those reflected rays projected forward, APPEAR to come from a VIRTUAL source, that is just inside the leader.
95% of the light propagates into the leader and is focussed BY REFRACTION to a much brighter REAL image of the sun, just to the right of the leader. That will have 95% of 95% of the incident light, due to the two interface splits, and is by far the brightest 'object' in the system, and is seen from a forward observer looking back towards the sun direction.
The second missing 5% (5% of 95%) is reflected by the CONCAVE mirror, which forms a seond REAL image just to the left of the leader right side (RED). So BOTH REAL IMAGES are in RED, on the right and left of the right side of the leader. The right side one 0.95x0.95 / 0.95x 0.05 or 19 times brighter than the left side one, and in air it is also 1bout ten times brighter than the ambient sunlight, so the left hand reflected image is about half of the direct sunlight brightness.
Those reflected RED rays, are then refracted and reduced in beam angle at the left side of the leader and emerge towards the viewer as yellow/mustard rays, not to be confused with the original green reflected rays.
That is the light that forms the flashes in Ralph's video. but he probably sees part of the original green reflection as well.
As for modelling accuracy, these light ray 'splits' are calculated using the full FRESNEL formulae for electro-magnetic energy splitting at a boundary between two media. Those equations in turn, are calculated using MAXWELL'S equations for electromagnetism, and electromagnetic wave propagation. Those are fundamental laws of physics that are known to be accurate (compared to experimental observations) to at least 8 significant digits of precision.
The velocity of light, which is calculated directly from Maxwell's equations, from fundamental electric and magnetic properties of free space, are the ONLY physical quantities, which have EXACT numerical values. It turns out that the acceleration due to gravity (g) is also exactly specified in value; but it is NOT a fundamental physical quantity, it is simply defined as having a specific value, and actual observed experimental measures are simply referred to that marker, and are different for every point on the globe.
So called "models" connected with "global warming" are based on "observations", which are actually "samples" of some physical quantity measurement; but they can't really be called "DATA", since those samples are not gathered within the constraints set down by the basic rules for sampled data systems (Nyquist's Theorem), so they are simply samples of "noise", and can't even be relied on to produce an accurate measure of the AVERAGE value of whatever variable they purport to be observing.
But it is true, that the results of Optical ray tracing, are in fact a simplification based on the RAY model, which is a simplification of the full EM propagation theory. It is valid for systems which are geometically large compared to the wavelength of the 'light' being propagated (0.55 microns in this instance).
I have been able to create an optical glass model for SEAGUAR fluoro-carbon; it is crude, and simply specifies that the 0.55 micron value for the refractive index is 1.42, and makes no claims for any other color.
I'll do both the nylon, and fluoro under water. There are some features in the software, that may let me unscramble some of the rays; such as plot only rays that have hit exactly two surfaces. If those filters are not too difficult to set up, I will do that. But it is costing me actual money to do this stuff, instead of modelling light bulbs for a paying customer.