Total reflection and fishies

Do you know the phenomenon that once you start noticing something, you see it everywhere? That’s been the case with me and total internal reflection. Not quite as impressive as last time, but still there:

And what I found really interesting this time: a swarm of tiny fishies making wave rings! I only noticed them because of those tiny waves. And if you look closely you can see so many of them just below the surface right where the wave rings are!

So funny to see the water almost boiling with fish on such a calm morning.

And another thing that fascinated me: how it’s so much easier to see into the water in places that are shaded (or dark) from the reflection of that pier. Not quite sure yet why it’s so much easier to see here, maybe just because there isn’t any glare? Any ideas?

Total internal reflection

Have you ever wondered why at some angles the sea looks blue (or whatever the color of the sky that day) and at others you can actually look into the water? That’s the phenomenon of total internal reflection. There is a critical angle at which you switch from “being able to look into water” to “total internal reflection”, i.e. the sky being reflected off the water’s surface and reaching your eye. Below you see a nice example of this: The more perpendicular you look at the water surface (i.e. those sides of the wave facing you), the better you can look into the water. Whereas all those parts of the sea surface that face away from you look blue and you can’t look into the water there.

I think this is totally fascinating! Don’t those pictures look almost fake?

And, btw, this doesn’t only happen if you look in parallel to the direction of wave propagation. Although it looks even weirder at an angle:

Can you see how all those tiny ripples on the wave each show the same phenomenon of either reflecting the sky or being transparent and showing the sea floor underneath? How cool is that? :-)

Awesome reflection of a wave train

This is a really good way to train your eyes to spot reflections of waves: watch a single wave train hit a sea wall:


Please don’t get sea sick when — about halfway through — I’m moving the camera around :-)

Wakes and what they do to the sun’s reflection

When I said that wake watching made me happy last week, did you really think those were all the wakes I was going to show you? Ha! No, I have plenty more! :-)

Today, I want to show you a couple that have one thing in common: the way that they show up against the sun’s reflection and thus become a lot more visible than they would be if they were just reflecting a uniformly blue or grey sky.





Reflected wake

The best ship-watching of the year happens during Kiel Week (even if I do a fair bit of ship-watching year round ;-))

But this year, I was absolutely fascinated with wake-watching. Look at the sailing ship below and its beautiful wake!


You very clearly see the streak directly behind the boat, caused by turbulence where the hull pushed through the water. And then there is the actual wake, fanning out from the ship.


And then that wake gets reflected on a sea wall as the ship is sailing past!


Watching things like this makes me happy :-)

Wave watching 

This is an old picture from early spring, but I just love how the reflection of that pier shows up the different wave lengths so clearly. The longer swell wouldn’t have been visible just from reflections of the sky…

Waves reflecting on a sea wall

I really like it when waves reach a sea wall at an angle, because the resulting criss-cross looks so cool :-)

And especially cool when you see it gradually building up, like below where the sea wall is partly protected by the gravel (or whatever you call those heaps of stones running in parallel to the sea wall?). The energy of waves hitting the sea wall at that part is dissipated, hence no reflected wave is sent off. However waves that hit the sea wall directly are reflected. Can you see how the reflections spread?

See it more easily in the movie below:

Playing with a thermal imaging camera

I recently borrowed a thermal imaging camera from work. So much fun!

Below you see a cold sky, warmer trees and two really warm people walking through the park.


One thing that really surprised me was to see reflections of the warmer trees on the little lake below. Although thinking about it, I am not sure why I should be surprised: If it was a “normal” image and not a thermal image, reflections wouldn’t surprise me at all. So why should thermal radiation behave any different?


But it messed up my plans quite a bit. I had hoped to maybe be able to see heat being transferred when waves crashed against the sea wall. But a) there were no waves, and b) what did the waves do? Correct: reflect the sky.  Just like they always do…

So this is what we see:


And this is what the thermal imaging camera sees:


On a different day you clearly see the warmer clouds:

As well as the apparently much warmer ships.

And looking down from the sea wall:


And what the camera sees:



Do you know the feeling when you, even on the most beautiful of days, want to get out of the pretty parks as quickly as possible so you can finally see the water?


Especially when it’s foggy?


And it is so worth it, there is always something to see. For example on that day: what a nice field of shallow water waves!


And what an awesome criss-crossing of waves being reflected on the sea wall on which I was standing when taking that picture.


And how sad that this lake was frozen over! :-)


P.S.: Still looking for a christmas present for your nerdy friend, your niece, anyone who should spend more time looking at water? Check out my book :-)