We're off on the four day walk on the Kepler track tomorrow and so today was a rest and re-stock day.
The Kepler track goes up the mountains that you can see in the distance in the 1st photo, including climbing to the peak of Mount luxmore, which is the pointy one just right of centre.
We popped over to the local wildlife sanctuary, which turned out to just be three aviaries. They were very proud of their Takehos and there was also a very bossy Shellduck, which insisted on being fed.
Te Anau is much bigger than Manapouri at least and there's a lot more going on here, including a cinema built especially to show a 30 minute film on Fiordland.
We also found the biggest and happiest eucalyptus tree we've ever seen. If you look closely you can spot Hannah to get the scale.
That's it from us for four days.... Let's hope the bad weather holds off and we get some good pictures in the next few days!
During this intermission, while Hannah and Dave explore regions where no human eye has ever set foot, it seems timely for an update on the question of glacial lake colouration. (Continued from a conversation under "Fox is wet")
ReplyDeleteRobbie is back, looking knackered (he is with child) and has pointed out that the general phenomenon we're looking at is Mie scattering. This is distinct from Ewe scattering, which of course accounts for the distribution of sheep under "One for Tim". It is a solution of Maxwell's equations, for a plane wavefront travelling past a particle. When the wavelength is >> the particle size (eg visible light passing atmospheric molecules) the scattering is exceedingly dependent on wavelength, greatly increasing at shorter wavelengths. This is Rayleigh scattering, which is why the sky is blue, sunsets red, etc etc. But when wavelength is << particle size - dust - the scattering is pretty independent of wavelength. In the region where wavelength is broadly similar to particle size - which applies to some of the rock flour in lakes - there's a quite sharp change from one regime to the other.
I have absolutely no idea where that leaves us, but I would guess rock flour has a size distribution that puts it into both regimes. Maybe the Rayleigh size bits give a colouration, whilst the bigger bits scatter it in a pretty, milky sort of way. Or something.
Discus...
Apologies: correction. The original thread is of course under "Fox Glacier".
ReplyDeleteWell, we're getting somewhere. I don't think I can really add much to this. We may have to go with "It just is" at the moment.
ReplyDeleteUgh. In London tonight. NZ looks very, very good!
ReplyDelete