At one point or another, you've probably heard the phrase "boiling hot" applied to a desert. But unless you watch the video above, you've probably never seen sand looking like it's actually boiling. Indeed, the sand in the video seems to behave more like water than, well, sand.
Want to see it on a bigger scale?
That sand basically looks like what happens to a pot of spaghetti when I get distracted by Twitter.
So what's going on? Believe it or not, the process is relatively simple. It's called fluidization. In both of these videos, air is being pumped into the sand from underneath. This air is separating the sand's particles and that separation causes the particles to flow a bit more freely, like the particles in liquids. The result is the sand ripples, bubbles and flows just like water — all without getting wet. These devices, by the way, are called fluidized beds.
The closest analogy, even if it isn't correct, is to think about the process of a solid turning into a liquid. When a material is in a solid state, the particles are packed nice and tight. As it melts, however, the particles loosen up and are able to move and slide past one another, becoming a liquid. Again, this analogy isn't particularly correct since the sand really isn't changing its state of matter. But it's a good way to better visualize what's happening.