float (up)on (something)
To bob, drift, or glide over or on a particular surface. Look at all the ducks just floating on the water! The paper airplane floated upon the air for a few seconds before sinking to the ground.
float (up)on something
to drift as if on the surface of something; to drift along through the air. (Upon is formal and less commonly used than on.) The little tufts of dandelion seeds floated upon the breeze. The fluff floated on the breeze.