The next morning one of the trays had three ice spikes in it. As these spikes form due to pressure of expanding ice forcing water up through the last point in the surface of the ice to freeze, I was surprised that such a small amount of water could support three spikes.
Two of the spikes were still open at the top when I took the above photo at 9:15am. The temperature continued to be below freezing point, and by lunchtime the spikes had grown further and then closed at the top, as can be seen in the photo below which was taken at 1:00pm.
Below is the central spike, 33mm high...
...and the left-hand spike.
Several ice spikes had also formed in an ice cube tray. The tallest can be seen in the photo below and was 44mm high.
More pictures can be seen in the ice spikes section of our main site.
