Work with ice crystal formation

Much of my work on the Cow House residency has been inspired by the work taking place in the Manchester Ice Cloud Chamber (MICC) at the Centre for Atmospheric Science. I mentioned previously in my blog about a visit I made to the MICC where I spoke to Dr Clive Saunders who showed me a few experiments I could do without the need for a multi-million pound piece of lab equipment.

The basis for this experiment is that water can remain liquid at temperatures below 0°C. This is called super cooling; water at below 0°C is said to be supercooled water. Supercooled water between 0°C and -36°C will form ice crystals only if it can form around a nucleus. This is called heterogeneous nucleation. The water must form around a nucleus such as pollen, dust or even bacteria. Supercooled water below -36°C will turn to ice without the presence of an ice nucleus. This is called homogenous nucleation. The water freezes ‘automatically’. I am recreating homogenously formed ice crystals.

Clouds that form higher up in the atmosphere consist of these ice crystals. An example of such a cloud is cirrostratus. These are whitish clouds, which form a very thin layer around 5.5km high. They indicate there is a lot of moisture in the air and can later descend to form other types of rain cloud.

In my first experiment, water vapour is put into a chest freezer at between 0°C and -36°C and supercooling occurs. Air at high pressure is added with a syringe and the temperature is reduced to below -36°C. Ice crystals then form in a bubbling chain reaction. I pointed a spotlight into the freezer and this showed up the ice crystals.

After figuring out how to do this successfully in the freezer, I decided the next step was to scale it up. I hired a refrigerated transit van and built a room with fabric walls, which could be slotted into the back. I tried out a few techniques with varying success. It is very hard to keep the van cool for long enough for the ice crystals to form. Using a pressure hose and air compressor was most successful. The fabric room is now a sort of corridor in my studio.

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