Sunday, October 21, 2012

Rayleigh, and a pencil sketch-



I've been promising to show you guys traditional hand drawn graphite-based art for like, what, half a year now? Mh, finally got around to it. Its not really much to show though, I was just drawing for the sake of the blog entry. Its just a regular three-quarter view face, with no reference to speak of. Holy mother of hairshits, though, that is one baller haircut. I guess im biased though, I have a certain affection for large mops. On heads, exclusively.

Myeah. In critique of myself, the back of his head is kinda... Missing. I mean, this guy really does have no cranium. Ive gotten too used to drawing people in this pespective, and I do it wrong. The back of his head should extend further. Its not really a difficult fix, but its something I dont realize when im drawing, because ive always done it like that. Anyway, in this particular drawing, the disproportionality of his hair in general accentuates the issue, normally it wouldnt have been a problem in this drawing, if only he didnt wear his quiff with such swagger.

Yeah, Quiff. Thats what that kind of hairstyle is called. I wear my own with great pride, like a beautiful lions mane. Haters will hate. And no, its not the same thing as or even remotely comparable to a queef.



Rayleigh was an old english fellow. A lord, actually. Thats about all I know of him as a person, but I do know he came up with what is known as Rayleigh scattering.

Rayleigh scattering is, in short, what makes the sky blue. The principle is based upon elastic scattering, which in essence means light is scattered without any loss of energy. Elastic scattering occurs when radiation of long wavelength crosses particles of a smaller size, and the ray is redirected. This also means that different parts of the visible spectrum of radiation will react differently to the same matter.

Thanks,  Wikipedia.

As you can see, blue light is affected wayy much more than red light. Aha, do you know why the sky is blue yet? No? So, the small particles in our atmosphere catch and scatter the blue light, which is part of the white light our beautiful sun graces us with. While the other wavelenghts of light go straight from the sun to our eyes, the blue, shorter and more energetic wavelengths are instead splattered all over the sky. This means the sun will look orangeish, and the rest of the sky will be blue. 

Well, what happens at sunset then? The sky turns bloody red! Yes, very fascinating, is it not?! Why? Well, it goes red, because the length of atmosphere that the rays have to pass through increases exponentially when the angle increases. I can actually provide you with a peripheral but fairly simple and versatile mathematical formula for that. Its smaller because its less important.

h/Cos(α)= L, where h stands for the height of the atmosphere, α is the angle between the incoming ray and the surface normal, and L is a measure of the lenght of atmosphere in which the ray will have to travel to reach the surface of the earth. The formula can be explained as such; 

The value of Cosinus of angles nearing 90 degrees will go towards 0. Cosinus of an angle of 0 degrees is equal to one. This means the height will be divided by a value between one and zero. Dividing by values lower than one will multiply the divided value. 

Example; 10m/cos (60)  --> 10m/0,5, because cos (60) gives a value of 0,5. This means that passing through something that is 10 meters thick at an angle of 60 degrees from the normal vector (which is equal to 30 degrees between the incoming path and the surface itself.), will force you to pass through (10/0,5 =) 20 metres of said area/matter! If the angle were 90 degrees, go fuck yourself, because we cant divide by zero, and logically the path would become infinitely long. If the angle is perfectly perpendicular to the surface, we would only have to pass through 10 meters of matter, because cos (0) is one.

Well, to be perfectly honest with you, the formula not applicable in this case. For a range of different reasons. I just think its an interesting formula, because it can be used as a shortcut in a range of different geometric situations. ANYWAY

Since the path which the ray will travel through atmosphere increases (Into infinity), so does the amount of scattering which occurs. When more and more blue light is discarded, for example back into space (which is why we can see the earths atmosphere as a bluish light from space.), only longer wavelengths of radiation persist. That means we have a shortage of blue, and a fair amount of green and yellow light, and an abundance of red photons --> BAM, REDDISH* ORANGE* BEAUTIFUL SUNSET. 

*(I coloured the words so you know which colours im talking about..!)

Rayleigh- and elastic scattering also explain why a bunch of lonely lightrays or sunshafts can be visible hanging in the air, if in an otherwise dark environment. Think discolights and lasers. In a disco theres often more than the components of normal atmosphere in the air though, so the scattering will be different.

Theres also something called Mie scattering that occurs in the atmosphere, which is a refractive phenomenom that has to do with how light is refracted in water droplets and dust particles in the air. But more about that on someone elses blog, I think thats enough sky-science for today.

Myep, some of you who lack base knowledge of how electromagnetic radiation works may experience difficulties grasping all of this, but atleast you now know that the sky is blue because some old english fart named Rayleigh came up with a theory about elastic scattering in the atmosphere.

I implore you to research further, and subscribe to this blog, because theres a whole world of stuff that you dont yet know about!


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