A general view on Sunglasses

The Sunglasses may be made with moreover prescription or non-prescription (i.e. plano) lenses that are darkened to give protection against bright visible light. Good sunglasses should as well care for against ultraviolet light. As a result of changes in the atmosphere, ultraviolet levels are greatly higher than in the past and ultraviolet protection for eyes and skin is even more essential. It is likely to have lenses that look very dark and however offer little ultraviolet protection. Sunglasses differ greatly and many offer more style than protection.
The Glasses with photo-sensitive lenses, called photo chromic lenses, become darker in the presence of UV light. Unluckily, many car windshields care for the passengers from UV light, while not protects from bright visible light, making photo chromic lenses ineffective where they are most needed. Still, they offer the ease of not having to bring both clear glasses and sunglasses to those who often go indoors and outdoors during the course of a day.
The Light polarization is an added characteristic that can be applied to sunglass lenses. Polarization filters take away horizontal rays of light, which can cause glare. The Popular among fishermen and hunters, polarized sunglasses let wearers to see into water when generally glare or reflected light would be seen. The Polarized sunglasses may present a few difficulties for pilots in that reflections from water and the other structures often used to gauge altitude may be removed, or the instrument readings on liquid crystal displays can be blocked.

A little note on Pace Car

A pace car has been used to begin the Indianapolis 500 since 1911. The first pace car was a Stoddard-Dayton driven by the Carl G Fisher. Further car and the motorcycle races have also used pace cars.
The intention of a pace car is to help and to give an organized running start to the race (as different to starting the race with all cars at a standstill). The racecars go after the pace car around the track, keeping their assigned pole positions.
The correct details can differ, but normally, there is one "parade lap" at a somewhat low speed. This is followed by greatly faster lap that directly leads to the proper start of the race, as the pace car turns off the track into the pit area.