I think it looks like snow floating in the river...but it's not! Frazil ice is small frozen water crystals or frozen mist from the waterfalls. To me it resembles slush and it floats on the surface of the water.
This does not happen every year, because the conditions have to be right in order for it to happen. And there are some years where it only happens for a couple of days. When it does happen, you will find it flowing in the Yosemite Creek here in Yosemite in the months of March and April.
These unique frozen water crystals that make up this slush occurs because the surface water in the Yosemite Creek is warmer than the water beneath the surface.
As the air cools down, the surface water looses its heat and cools the surface water quickly. Because the water in the river is moving, small ice crystals form. The ice crystals are pushed to the bottom of the creek.
Yosemite Creek is what flows out of Lower Yosemite Falls.
When the ice crystals are pushed to the bottom of the moving creek, they multiply. There is approximately one million crystals per cubic meter. The crystals attach themselves to things in the water. As the crystals attach to objects under the waters surface, a dam forms and the water must find a new way to flow.
As an added bonus, when the frazil-ice is flowing, this time of year does not bring the crowds to Yosemite National Park. Therefore, you'll find the park is quieter and more peaceful. March and April are a very nice time to plan a trip to come and see Yosemite National Park.
As the waterfalls continue to flow in the winter, the mist from the falling water freezes. It forms a snow cone at the base of Yosemite Falls. The snowcone melts when spring
comes. Watch the moving picture to the right and you can see the snow cone forming. What happens is that layers of ice will freeze to the granite walls during the winter months. As
the weather warms up, ice sheets melt or collapse and add to the snow
cone at the bottom of the waterfall.
Snow Cone Forming At the Base Of Yosemite Falls