I've co-supervised BSc students on the topic of ice nucleation in clouds. Did you know that only large amounts of water freeze at 0 degrees Celcius? Liquid water below 0 is called 'supercooled' and needs a 'reason' to start forming ice. This can be a shock, or an impurity where the ice can form. 🧵👇

a glass of water is being pour...

Large amounts of water (larger than a drop) have enough impurities for freezing to start at 0 degrees. For smaller drops, this becomes a game of chance and depends on the impurities. This means that water drops in clouds do NOT freeze at zero! We still don't fully understand when drops do freeze. 🧵👇

dr. Isabelle Steinke her research focusses on this: when do drops freeze and how does that depend on impurities? Frozen clouds behave very different from liquid clouds, so this is important knowledge for weather and climate models! I get to co-supervise BSc #physics students together with her. 🧵👇

This quarter two students worked in tandem: Duco improved the experimental setup we are using: a real 'design' assignment where he build on what he learned in my 'Design Engineering for Physics Students' course, for example using a 'morphological chart' to decide which improvements to focus on. 🧵👇

Fellow student Wibe used the setup to study how the freezing points of pure water depends on drop size, and how contamination with soot as 'ice nucleation particles' changes this. This video shows pure on the left and soot on the right. Turning grey means freezing. Check the temperature and time! 🧵👇

However, repeat experiments show a large deviation between similar experiments for pure water and all of them at higher temperatures than derived from classical theory. We hypothesize that this theory makes assumptions that don't hold. 🧵👇

But to make that claim stronger, in follow up research we need to reduce the uncertainty in our measurements even more. We will follow this up when a next student steps forward to continue this work. I love this collaboration between @tudelftceg.bsky.social and @tudelfttnw.bsky.social :-) 🧵👇

Later today I will continue this thread, describing how multiple MSc students worked on answering "how does plastic beach?" 🧵👇

"How does plastic beach?" That was the title we used for a potential MSc thesis research. And yes, that was a reference to the #Gorillaz album. But it also an active area of research. We all know plastic pollution is a problem and many researchers are trying to understand different aspects of it! 🧵👇

One of the open research questions is: "under which circumstances that plastic from the sea and up on the beaches?" Is it wind? The shape of the waves? The type of plastic? All of the above? We asked for a student to look into that and instead: we got three! Iris, Camilla en Leanne! 🧵👇

Starting last January, for their 6 month MSc thesis work, each of them tackled a different aspect of the dynamics of beaching of plastics. Camilla and Leanne in the lab using a waveflume and Iris in the field: on the actual beach! together with @annebaar.bsky.social I got to supervise them! 🧵👇

In the lab Camilla focussed non the shape of the waves and Leanne on the density of the plastic. In our @tudelftceg.bsky.social waveflume we can control the shape of waves very accurately. They created breaking waves and dropped plastic in before the breaking. 🧵👇

The plastic is filmed with three go-pro camera's above the flume. Spot the proud supervisor having a look at the experiment. 🧵👇

This video can be analyzed with software to track the particles! 🧵👇

This gives raw data on particle position in the flume. 🧵👇

From this they could calculate speed per "wave zone" (shoaling, breaking, surf...) and analyse how that differs for either different waves (Camilla her thesis) or different densities of plastic (Leanne her thesis). 🧵👇

But knowledge from the lab needs to be confronted with reality! So Iris did fieldwork: using a drone to track the movement of plastic debris in the surf zone of the beach near The Hague! She made this amazing video of a day in the life of a fieldworker! 🧵👇

With data from the field you can't control different factors, so Iris needed to make analyses which combined everything, such as these violins plots. 🧵👇

The work of Camilla, Leanne and Iris combined helps us better understand under which conditions plastic pollution ends up on beaches. But it also clearly showed how much we don't know yet: lots of research still to be done! 🧵👇