The water is mixed with snow that gradually flows from the basin.
Normally, lumps of snow flowing in water would melt and become smaller, but these lumps seem to be getting larger.
Here is the downstream.
The lumps are larger than when they were upstream. They also don’t move in the same way normal lumps of snow should.
You know, most ice would just float on the surface. But this floats and then it sinks again and it can turn over. It’s really strange stuff.
It’s hard to describe. I mean I always tell people it’s like a slushy, a drink, you know, a frozen drink, a Margarita or something like that.
Steven suggests going even further downstream.
They’re now deep in the forest. Here, the river is flowing more slowly.
And the lumps of snow start clumping together.
After a while, they stop moving altogether. What exactly is happening?
What causes this phenomenon?
So it has to be cold. It has to be below freezing to form. And what happens is that when the water goes over the water fall, as it turns into water drops, it actually loses a little bit of temperature, so it gets below freezing. So this makes a very different ice crystal.
On a cold spring morning, the water from Yosemite Falls gets below zero as it cascades down from the tall cliff. It transforms into a mysterious kind of ice.
Steven recreates this phenomenon in an experiment.
First, plastic bottles filled with water are cooled down in an ice chest. Salt is added, so the surrounding water is well below freezing.
When water is cooled slowly at a low temperature, it becomes supercooled water. It doesn’t freeze - even if the surrounding water is below zero.
When it’s poured over ice…it quickly starts to freeze. The ice isn’t hard, but rather, it’s soft because it contains water. This is the same type of ice that flows down from Yosemite Falls. It’s called frazil ice.
When supercooled water falls into the basin, the shock results in the formation of these special ice crystals.
These ice crystals grow to a size of a few millimeters and look like tiny branches stuck together. They become entangled and end up forming lumps of ice.
This frazil ice fills the lower stream of Yosemite Falls.
Rising and sinking in the water, these lumps rapidly make their way downriver.
After the sun rises and the air gets warmer, the ice will melt and disappear before the day ends.
With a quick return of cold weather, Yosemite Falls produces frazil ice, a magical phenomenon created by special conditions that only exist at the base of the waterfall.
Yosemite Valley was designated a UNESCO World Heritage site in 1984.
The great rocky cliffs attract people from all over the world.
The sheer precipice up ahead looks as if it was cleanly cut with a sharp knife.