sunlight is partially polarized by atmosphere

book/pages/waveguides_polarization.ipynb

@@ -74,7 +74,7 @@
    "id": "c9cefbbe",
    "metadata": {},
    "source": [
-    "Natural light (say, the light from the sun) is *unpolarized*. That's not to say that the light doesn't have electric and magnetic field components, all light does, but the orientation of the electric and magnetic field components is scattered and non-uniform. It's possible to polarize unpolarized light by filtering out light with certain polarizations and permitting light with other polarizations. Once light is polarized, it's a lot more useful for transmitting data. Polarized light behaves predictably, unpolarized light behaves unpredictably.\n",
+    "Natural light (say, the light from the sun) is *unpolarized* (well, mostly--when it scatters from molecules in the atmosphere sunlight becomes partially polarized). That's not to say that the light doesn't have electric and magnetic field components, all light does, but the orientation of the electric and magnetic field components is scattered and non-uniform. It's possible to polarize unpolarized light by filtering out light with certain polarizations and permitting light with other polarizations. Once light is polarized, it's a lot more useful for transmitting data. Polarized light behaves predictably, unpolarized light behaves unpredictably.\n",
     "\n",
     "The behavior of light in a waveguide depends in part on its polarization, which we'll explore in the next section. Some waveguides support light of certain polarizations and not others in certain modes, and most waveguides can support multiple photonic signals of different polarizations simultaneously."
    ]