Light scattering off of atoms does impart a force on them, but for visible light on air, the effect is very small and not easily noticeable. Take for example a 500nm photon scattering off of an oxygen molecule. The momentum of this photon is 1.3x10-27
Newton-seconds, and if scattered by 180°, then it would change the velocity of the oxygen molecule by about 2.5 cm/s. This is a very tiny fraction of the average velocity of oxygen molecules in air at room temperature (nearly 500 m/s).
You might think that with so many photons of sunlight streaming in constantly, the effect would build up and blow all the air away, but what instead happens is that because the atoms are also quickly colliding with one another, any additional velocity gained through scattering photons is quickly converted into random (thermal) motions of the atoms and re-radiated as heat. So no net effect is accumulated.
An example of where the pressure applied by light on atoms does become noticeable is clouds of gas around hot stars. In those environments the light can be very effective at pushing the surrounding gas away. Another important example is the stars themselves -- it is literally the radiation pressure supplied by all the photons streaming outward from the core that supports a star against collapsing by its own gravity.
Propulsion Disk wrote:What do you mean by atomic erosion?