Specifically, the grey lens is the most common type of lens colour. Transmits all colors evenly without changing value of color. Light enough not to impair vision, yet dark enough to provide overall protection from glare. Excellent for bright sunny days. Grey tint is best for bright light situations like outdoor sports because it blocks out the brightest of the suns rays.
Brown, warmer lenses are especially good at blocking the blue light commonly found in diffused light such as one might experience on a cloudy day. Brown can improve both contrast and depth perception, reduce glare and is a good all-around choice if you live in an area with changeable weather patterns. Brown is also best for lower light situations, like riding in the late afternoon or early morning. Brownish tint lens helps highlight the different contrasts in green colors and enhance visual acuity on the golf course