Remember I did this for work?
We ended up with pretty cool pictures, like this one:
And as I was standing in the water, guess what I was doing? Taking pictures of the ring waves propagating away from my feet! :D
And I find it so amazing how you can start a wave train moving away from you, and then just have it grow bigger and bigger and completely calm in the middle.
That’s the stuff that makes me happy :-)
One last picture, because it’s just sooooo beautiful!
A week ago already, Frauke and I went on an evening walk in Kiel Holtenau. Beautiful wave watching to be done there as always! Here you see the one side of a ship’s V-shaped wake approaching our vantage point. You can see the individual “feathers” of the wake: Short wave crests, all parallel to each other, but slightly shifted to the side to form a straight line (well, two straight lines to form a V with the ship at its tip, but the other side of the V is not visible on this picture).
And this is what it looks like when the wake has moved past us: Looking on the back of the feathery shapes. The ship that made all these waves has long sailed away.
Anyone who has ever read my blog, seen my Instagram, or met me in person knows: The ocean is hugely important for me. The ocean is important for my mental health, looking at water just makes me happy and calm and content. The ocean is also the foundation of life on this planet: It supplies more than half the oxygen we breathe, it moderates temperatures such that I am happy to go swimming in Kiel fjord all year round (ok, that’s also because I am slightly insane), it provides us with food, work, goods.
Today, on World Oceans Day, let’s celebrate the ocean by looking at one specific aspect in which it is amazing, and that is in how much energy it contains. In heat that is stored in it. In dissolved salts. In its movement. You know I am addicted to wave watching, but there is so much more you can do with waves than just watch them, even though that’s not as easy at it seems.
One of my favourite wave watching spots is a broken prototype of a wave power plant close to my friend Elin’s cabin on an island off Bergen. The location was chosen for the enormous wave power that slams up on the coast here most days, and that’s also why the prototype unfortunately didn’t last very long.
In the movie below you see the spot where a turbine used to sit which would be powered by water pressing air up by being funneled into a sub-sea reservoir, and then sucking air back out when the wave retreats. And you see how, by the way the funnel is built, the not-so-enormous waves outside get translated into quite a change inside that hole. Wait for the splash! Can you imagine the movement of the air column above, where the turbine used to sit?
We weren’t even there on a particularly wavy day, so imagine the powers at work here on days with a lot of waves! The forces at work here are enormous. And just because we haven’t figured out yet how to make wave power work well in the ocean’s harsh environment, that doesn’t mean that it isn’t figureoutable!
Picture by Elsa du Plessis, used with permission
Even looking at these pictures and the movie I feel the effect the ocean has to me — giving me a sense of calm purpose and inspiration. Enjoy your World Ocean Day, and make sure to appreciate some water somewhere today! :-)
I have too many soap bubble pictures from last weekend’s trip to Kleinwaabs to not write a post about soap bubbles. So let’s get right into it!
First thing I never actually thought about: Why do you want soap to make soap bubbles? Soap lowers water’s surface tension (and see my favourite surface tension experiment here!), so wouldn’t that make bubbles more fragile than just using water? Turns out that without soap, there are hardly any bubbles because water’s surface tension is so high that it tends to lump water together into compact round shapes: so just drops, no bubbles. Which I should have known right away, obviously. So we need the soap as surfactant to keep the insides of the soap bubble apart and prevent collapse into drops.
So let’s look at how soap bubbles form. When someone (Frauke in this case) blows at the soap bubble wand, at first something resembling a wind sock forms (see above). Only after a little while it detaches and closes off bubbles that float away.
Soap in soap bubbles also produces the surface films that make soap bubbles look so pretty. And if you look at them closely, you can even see currents on soap bubbles as water and soap are flowing around on the surface!
Those currents are also one of the mechanisms that will ultimately make the bubbles pop: As gravity pulls the denser water to the bottom of the bubble, the soap concentrates on top. The more soapy the water, the lower its surface tension, so at some point the surface tension becomes too low to keep the bubble together — it pops.
Another mechanism making bubbles pop is just evaporation: As bubbles have a large surface, water evaporates fairly quickly from it, thus leaving more and more soapy water in the bubble. Until, you guessed it, the surface tension becomes so low again that the bubble pops.
A third reason for bubbles popping is also them floating into something which then breaks the surface. If bubbles float into other bubbles, though, this usually doesn’t result into them popping — they stick together and form interesting shapes of round segments and straight dividing walls. Surface tension always tries to minimize the surface area, balancing inside and outside pressure, so these are the energetically best shapes.
Interesting how that sometimes happens, while other times bubbles float nicely their separate ways, sparkling and shimmering in the sun.
And funny how difficult it is to take pictures of soap bubbles. Thanks for your patience, Frauke! :-)
On our work trip to Brodowin to prepare the GEO-Tag der Natur (which will take place here only a little more than a week from now! Crazy!), I had the chance to do some cool wave watching on different lakes.
Above, for example, you see wind waves coming in from the right, and their very distinct reflection on the left row boat.
Below, at the stern of the left row boat, you see a sudden gust of wind, causing lots of capillary waves, and thus high surface roughness.
And below, what would you guess is the secret to the ring waves radiating away from the end of the pier? It’s a surf board, bobbing up and down in the incoming wind waves!
I just love looking at water, it has such a calming effect on me, even in 35 degrees heat (which I am really not good with).
I love to see how the more lively wave field offshore gets calmed down as only longer wave lengths make it through the water lily frequency filter! And how the wave crests get bend as they reach the shallow shore.
Now, different lake. This one is 38 m deep! Would you have guessed that?
Here you see that we are standing on the downwind side of the lake: Smooth water on the other edge in the lee of the land, then, after sufficiently large fetch, waves that grow more and more the further they have progressed over the lake.
Same lake, same phenomenon, different view.
And the last bit of the lake just to give you an impression of the glacial landscape it is situated in, explaining the very steep slopes and the 38 m depth.
This would be such a lovely place to sit at and enjoy the view, if only there was a little shade…
I find it fascinating how the shape of the waves doesn’t change as they approach the shore. That’s because the shore is so steep that when, at last, the waves start feeling the bottom, they have already reached the edge of the lake and didn’t have time to change their shape.
Same phenomenon, different view.
Water is just so amazing :-)
Yesterday, I happened to be at Parsteiner See for work.
At first, the sea was completely calm and the only waves were the ones we made doing our photo shoots, like so:
Other than that, the lake was completely calm.
But then suddenly, I spotted a breeze going over the lake. It becomes visible in the dark areas with higher surface roughness, where capillary waves have formed.
As the wind keeps blowing over the capillary wave area, those waves grow and then at some point become “regular” gravity waves, that travel out of the region where they are directly forced by the wind. See below: In the background you still see the area with higher surface roughness, whereas in the foreground gravity waves are coming towards the shore.
As the wind keeps blowing over the surface, forming capillary waves over larger and larger areas, those areas all show up as darker and rougher.
And the cute little waves keep coming to the shore :-)
Did you notice that most tourist ships on the Spree in Berlin don’t actually have nice bow waves? Luckily I found one that does! (see above)
Because what then happens is that a nice wake develops, too. Below you see the turbulent wake right behind the ship, and the feathery V-shaped wake (with the ship at its tip) spreading out.
And what’s really cool is how that V-shaped wake gets reflected from the sides of the Spree, coming back towards the middle. Can you see the two wave fields?
And once they meet in the middle, you get a really cool checkerboard-like interference pattern!
And yes, that’s the German Parliament in the background…
Below, you see the wake of a coot (apparently, according to my dictionary. I will call it duck for now…).
And now the duck’s wake and a ship’s bow wave!
Do you make everything you see about your favourite topic, too? Then check out this month’s #scicommchall!
What I find really fascinating about watching waves in the atmosphere rather than on water is that all the waves that become visible are not surface waves like on water, but internal waves. Which we have to go to great lengths to make visible in water (for example by adding dyes in tank experiments) but which we can’t just visually observe in the sea in the same way as we can in a transparent atmosphere.
In the atmosphere, however, we also don’t see every internal wave going on, either, we need very specific conditions for them to become visible. So whenever I see one, I start pondering why we see exactly what we see, why there are clouds in some places and not in others. Below, for example, we see the troughs of an internal waves in cloud stripes, but the crests don’t form clouds. Fascinating how just displacing air by a little bit can cause clouds to form and to disappear!
And things become super cool when you combine atmospheric wave watching with “normal” wave watching like in the picture above. There you see the rough surface with tiny little wind waves in the background, waves coming around the break water, the calm water in the lee of the break water, sheltered from the wind, and then the reflection of the atmospheric waves on the water.
And you thought it couldn’t get any better? Well, you were wrong! Now there are also some waves on the water, plus soap bubbles! :-)
Now, for a thought experiment: What would soap do to the waves? Would destroying surface tension actually matter? I think not in this case, or t least not close to land in the picture above, since the waves are mainly gravity waves, not capillary waves. But what do you think?
On Thursday I went on a “let’s go for a walk, but if it starts raining too much, we’ll just go have coffee” trip with a friend to the east shore of Kiel fjord. And it’s always nice to get a different perspective!
For example below: You see the large cranes from the shipyards that are the most noticeable thing in Kiel’s skyline in the background. And you see that it’s quite windy: Lots of nice waves coming on the shore! From how they don’t change their direction as they approach the shore we can see that the beach must have a much larger slope than the one for example here. If there was a shallower slope, they would turn such that the crests would arrive at the beach more or less parallel to the water line.
We also see that it’s quite windy by the streaks that form in downwind direction, and by the small choppy waves that are forming on top of the larger ones. Can you feel how the wind is coming in in gusts wherever the surface roughness of the sea is increased?
What I found really surprising is how much of a wake the windsurfer created. The board was gliding on the water, yet clearly entraining a lot of air into the water so that we very clearly see its trajectory. I would not have expected that!
And here is a picture of diffraction of waves in a, what I like to call, half-slit experiment. Basically the wave breaker thingy acts as an obstacle and a very wide slit starts where the obstacle ends. See how, once they pass the wave breaker, the wave crests get shaped into quarter circles that run out into straight wave crests away from the shore?
Here is another view of the same situation; of waves being diffracted by the wave breaker. I quite like the difference in surface roughness: As soon as the waves run into the lee of the wave breaker, they are sheltered from the wind and their surface becomes smooth.
But the main reason I took the picture above is that I try to incorporate some stuff that relates to my job in my pictures, i.e. things related to biodiversity. Did you know that that kind of rose is apparently an invasive species? I did not and I find it baffling since it is very common on the German North Sea and Baltic Sea coast. And so pretty, and it smells so nice, too!
Below is a less pretty picture, just to show how the harbour’s breakwater has a big effect on the wave field. I guess that’s exactly what it’s there for, but it’s still nice to see…
But now it’s time for coffee. And to look at the rain from the other side of a window.
I always love looking at raindrops on windows! The picture below is just a blown up part of the picture above. Do you see the all the tiny, upside-down reflections of the ColorLine in each of the raindrops? How cute is that?
It’s nice to sit inside and just watch the ships go past and listen to the rain :-)
On a bike tour with my friend Frauke in Greetsiel two or three weeks ago, she pointed out how well one could see that the waves on the puddles left in the Wadden Sea close to low tide were wind-generated. That was that for the bike tour — now I had to take pictures.
Below you nicely see the ripples that are created where there are longer stretches of puddle aligned with the wind direction, i.e. where there is enough fetch. And you see how the waves get diffracted behind topography, fanning out downwind of slits! The wind is coming from the right here, almost in the direction pointed out by the looks-like-an-arrow-but-is-plastic marine litter.
Here we are looking in the opposite direction, the wind now going left-to-right. Do you see the one slit in the lower half of the picture and how wave crests propagate almost perpendicularly to the wind direction, just because there are waves going through that slit? Pretty cool, me thinks!
The really shallow water with all the stones in it made it really easy to look at waves from different directions. Below, we are looking downwind, at the back of the waves.
And below we are looking upwind. See how different things look now? You still see the wind pushing the waves, the front slope of the wave is a lot steeper than the back slope.
I love the picture above, makes me want to put my hand in the water and play with the waves :-)