Air, light, electricity and radio waves I studied physics long ago, but now I am an RF technician studying for a Ham radio license. So, I apologize if this is a dumb question. But here it is: Why does air let light and radio waves through easily but obstructs the flow of electricity?
 A: Electricity is the flow of a physical particle (with mass) called the electron, it must move from atom to atom for example.  Air is less dense, molecules are barely in contact, the electrons are also held tightly in air molecules.  Light is a completely different thing, think of it as a wave (it can also be consider to have particle behaviour) in something called the EM (electromagnetic)field, the field is theorized to be everywhere in space, and light particles/waves are called photons. Photons have a wavelength property (think size), air can transmit many photons but not some types of photons due to the wavelength. 
A: Lightning is the flow of electricity through air.  So, it does happen but it requires a monstrous potential difference to cause the breakdown of air that ionizes the particles allowing them to conduct electricity.
But, that is a very special case.  I am a ham radio operator and there are a whole variety of situations where conductivity or ionization of the air is important to ham radio -- in particular of the HF bands (160 thru 10 meter bands).  The Ionosphere is very important to long distance (aka DX) communications where the EM wave is reflected back to earth from the Ionosphere.  This reflection is due to the plasma of charged particles at this layer of the atmosphere.  Particles are charged by ionization, hence the name Ionosphere.
You might consider joining (if you haven't already) the Ham Radio stack exchange forum: Amateur Radio SE.
A: Light and electrons can be treated as waves, and one good example is the electron microscope. The sample is "illuminated" not by light, but by electrons. The electron beam is deflected by magnets, that play the role of lens. 
But it requires vacuum, because the molecules of air scatter the electrons. And it happens because the wave length of the electron is too small, ($10^{-10}$m) about the same size of an atom. 
Light has wave lengths in the range of $10^{-7}$m or 1000 times bigger. Radio wave lengths are several orders of magnitude greater.     
