Imagine millions of water molecules suspending in the air starts to turn into snow, I like to know the exact reason why we cannot have snow bow, is it due to the speed of each snow falling very fast or most of the light is reflected instead off the surface of snow?
Water molecules do not produce rainbows, water droplets do. A spherical droplet of water refracts light in a specific way that creates a rainbow. Snow is not spherical and instead of refracting visible light it mostly just scatters it. So snow appears white instead of creating a rainbow.
Not exactly snow but ice crystals suspended in the atmosphere do produce halos. https://apod.nasa.gov/apod/ap181221.html You can see the colors too. I am guessing that the snow flakes are too large and are not transparent venoygh to refract light