Daily Archives: February 10, 2025

The accompanying photo was taken by Daniel Dettmers in the morning of February 4 on frozen Lake Kegonsa. The high on the previous day was 37°F. This caused puddles of water to sit on the ice of Madison’s regional lakes during the day. Tuesday morning’s low temperature was below 20°F with calm winds.  These are just the right conditions to form what are called ‘ice spikes,’ as shown in the photograph.

When water freezes, it expands and becomes less dense. Ice floats on water. But if the lake ice is thick, when puddles form on a warm day, they sit on the ice surface.  With the cold nighttime temperatures, the surface of the puddle freezes, trapping liquid water below. As the puddle freezes, it can leave a small hole in the surface of the ice. Continue reading →