I saw  [this video][1] on levitating a denser liquid on less dense air by vertical shaking. But I couldn't understand some points in the video. 

**1** : How did the liquid levitate at [0:37 ][1]  or at any one of those moments?

I think it's because of vibrating the air in the vertical direction, which causes it to apply a force on the liquid in the upward direction.

Is there any mathematical model of this force  so that we can find the exact frequency for this levitation?

  [1]: https://youtu.be/bodsuTucSxQ