If I have a soap bubble then it will move rather randomly upwards perhaps due to the initial force from me blowing it, and eventually take ground moving downwards.
Another answer to a similar question was
A bubble, while it still exists, is balanced by three factors:
- Surface Tension of the soapy water.
- Internal Pressure applied by the air inside the bubble on the surface.
- Atmospheric Pressure.
Now those factors don't take into account the initial force for the blowing of the bubble and does that really explain why the bubbles rise for some time instead of directly just falling?
Best Answer
The air you exhale is in most circumstance warmer than the ambient air temperature. This is the air that ends up in the bubble. Due to the density difference (hot air rises), the soap bubble will rise. In my experience, bubbles do not keep rising, indefinitely. Thermal equilibrium is quickly reached, and the driving buoyancy force disappears. The gravitational force on the water will pull it downwards, but most likely the bubble bursts before you can observe this.