Three Icicles
Three icicles show how adding impurities (in this case, sodium chloride) to the freezing water creates ripples. University of Toronto physicist Stephen Morris and colleagues grew these icicles in the lab to examine their physics.
Natural Icicles
Icicles found in nature share this ripply surface. The ripples have a consistent wavelength of 1 centimeter, and researchers aren't yet sure why.
Distilled Water Icicle
A lab-grown icicle about 2 feet (65 cm) long made with distilled water. Without impurities in the water, the icicle is ripple-free.
Slightly Salty Icicle
Adding sodium chloride (salt) causes ripples to form on the icicle.
Very Salty Icicle
Adding more sodium chloride increases the ripple effect.
Clear Ice
Icicles form on a porch overhang. The physics of icicle formation is complex, according to the University of Toronto's Morris, because the water that forms icicles is supercooled.
Lab Icicle
Supercooled water forms "spongy" ice, so that not all of the water is frozen. Some is quarantined in tiny liquid pockets.
Ice Row
A row of icicles on a fence in Ottawa. These regular icicles form because of the natural instability of a water film on the horizontal edge of the fence, which creates drops a regular distance apart, according to Morris.
Church Icicles
Icicles line church eaves in Montreal, Quebec.
Icicle Melt
A drop of water falls off a melting icicle.
