# Tag Info

### Why can't thin clouds form rainbows?

Clouds are complicated. There are lots of different types of clouds, which may be composed of spherical or non-spherical water droplets, with uniform or non-uniform sizes; planar or columnar ice ...
• 91.7k

### Why can't thin clouds form rainbows?

You only see a bright, first-order rainbow when you are looking toward rain or mist and the Sun is behind you. Also, You said, "Sunlight easily passes through thin layers of cloud." That ...
• 15.3k

### Snell's law for the $D$ field

The derivation of Snell's law is indeed derived by assuming that the component of the E-field parallel to the interface between the two materials is continuous (i.e. the sum of the parallel components ...
• 133k
1 vote

### Snell's law for the $D$ field

Snell's law depends on the linearity assumption that $\bf D=\epsilon E$ (In Gaussian units, where $\epsilon_0=1$). This is used at the start of derivations to eliminate $\bf D$.
• 1,818
1 vote

### Why can't thin clouds form rainbows?

As hinted at in the last paragraph of @rob's answer, cloud droplets are simply too small to achieve the diffraction-limited angular resolution needed for the color bands to be distinguishable. ...
• 6,186
1 vote

### The angle of the prism for which there is no emergent ray will be, if its critical angle is $i_c$?

You are right. There is an error in the linked answer. The first two equations should be: $\sin(i) = \mu \sin(r1)$ $\sin(e) = 1/\mu \sin(r2)$ The ratio $\mu = (N2/N1)$ has to be inverted for the ...
• 6,606
1 vote

### Are laws of refraction incomplete?

You just have to think about the definition of the angles and what Snell's law says. Since angles are counted from the normal with the boundary, the angle of the transmitted light ray in the second ...

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