Tag Archives: Kleinwaabs

Wave watching in Kleinwaabs — and my first real Insta story!

So today (and tomorrow and the day after) is the big event that I have been working towards all year in my not-so-new-anymore job: The GEO-Tag der Natur! If you are curious about what’s going on there, check out our Instagram account @geo.tag.der.natur that Kati is doing an amazing job with!

As you can imagine, the weeks running up to this weekend were quite busy and a little stressful, too. So last Sunday I went to the beach to hang out with friends and do some wave watching! Because nothing has a more calming effect on me than watching water…

For example below we see nicely the effect of the wave (and wind) breakers on the wave field. In the lee of the wave breaker, the water is completely calm, whereas towards the right of the bay waves form and grow larger and larger.

And below we see a pretty cool “diffraction at slit” example: Straight wave fronts reach the slit between two wave breakers, and as they propagate through the slit, they become half circles.

But to relax and get my thoughts away from my job, I tried something new: I created and posted my first ever Instagram story! I’m not quite sure it’s my format, but I definitely had fun! What do you think? Would you like to see more of those? (I only just realized the story is in german and my blog in English. Posting anyway… Would anyone like to see this kind of stuff in English? Then please let me know and I’ll see what I can do…)

(P.S.: Since I made this for Instagram, the format of the video was optimized for viewing on a mobile phone. Therefore it looks crap embedded in a blog. But some you win, some you loose…)

What do you do to relax and get your mind off of work? Wave watching and posting about it on social media? Have you ever tried that? Or what else would you recommend?

Soap bubble musings

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! :-)

Atmospheric & water wave watching

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?