Why can air accommodate more water when the air has a higher temperature?
For a substance to be a gas, the kinetic energy of the molecules that make it up must be higher than the electrostatic potential energies that hold it together. When we talk about air "holding" water we are really talking about the amount of water that would be in the vapor phase relative to the amount that would be liquid at equilibrium.

Since temperature is a measure of the average kinetic energy of molecules, as the temperature increases, the fraction of water that can exist as vapor increases. Since air is already a gas under any conditions where water vapor can exist, it looks like the air "holds" more water as temperature increases.