We found this ice stalagmite under a drip from the greenhouse gutter. Why did the water freeze and build upwards instead of just flowing out horizontally? It must have fallen as a liquid. It occurred to me that ice must be a reasonable conductor of thermal energy because it feels cold to the touch. Its thermal conductivity is about 2 Watts per metre per Kelvin, compared to 0.59 for water and 7.8 for manganese, which is apparently the lowest for a metal. The figures suggest that the ice in the bucket can conduct thermal energy away from the falling drip fast enough to cool it below freezing before the liquid drop has time to run off.
