The physical identity of air is darkness. However, in presence of light, Air appears colorless. Dense air appears white. A vast expanse of air appears BLUE. Shallow water appears colorless. Solidified water appears white. Deepest water appears BLUE. When you look at the sun after you have mitigated it's blinding rays, it appears BLUE. Why is this so? Because it's a portal connecting the physical realm of bodies to the astral realm of spirits. The ground of the realm of the dead is deep waters and thus it's nature is deep darkness. The spirits take the likeness of the waters. Air symbolizes living spirit. Water symbolizes dead spirit.