Nimbryn: Mie Scattering Clouds
Cosmology & the Sky arc, page 160 of 193. Back to The Pixelated Physics Universe
Who they are
Nimbryn has one line, and says it often: “Mie scattering. no filter saves you.”
Nimbryn is a character of the Cosmology & the Sky arc: drawn in pixels, ruled by one piece of real physics, and never allowed to break it.
The physics
Mie scattering by cloud droplets (size ≫ λ) is nearly wavelength-independent, so clouds are white or grey.
$$ \begin{gathered} x = \frac{2\pi r}{\lambda} \gg 1 \;\Rightarrow\; Q_{\text{ext}} \to 2 \end{gathered} $$
| Symbol | Meaning | SI unit |
|---|---|---|
| $x$ | size parameter | — |
| $r$ | droplet radius | m |
| $\lambda$ | wavelength | m |
| $Q_{\text{ext}}$ | extinction efficiency | — |
Sources
- G. Mie, Ann. Phys. 330, 377 (1908)
- C. F. Bohren & D. R. Huffman, Absorption and Scattering of Light by Small Particles (Wiley, 1983), §4.4
Crossovers
Nimbryn meets Drycrest (Precipitable Water Vapour). Nimbryn's clouds block all wavelengths. Drycrest's water vapour absorbs specific infrared and submillimetre bands. Both are reasons observatories are built high and dry.
Nimbryn meets Thermal Mirage (Heat Refraction / Optical Distortion). Nimbryn's cloud droplets are comparable to or larger than the wavelength, so Mie scattering whitens all colours equally. Thermal Mirage bends light without scattering it, through gradients in the air's refractive index. Both shape what an observer sees of the sky.
Wear the lore
Concept keywords: Mie Scattering Clouds, Nimbryn, Cosmology & the Sky, physics lore, Pixelated Physics