We are not sure why it is so effective, just try this method when it rains heavily.
This method was told by a Police friend who had experienced and confirmed it. It is useful...even driving at night.
Most of the motorists would turn on HIGH or FASTEST SPEED of the wipers during heavy downpour, yet the visibiilty in front of the windscreen is still bad.....
In the event you face such a situation, just try your SUN GLASSES ( any model will do), and miracle!
All of a sudden, your visibility in front of your windscreen is perfectly clear, as if there is no rain.
Make sure you always have a pair of SUN GLASSES in your car, as you are not only helping yourself to drive safely with good vision, but also might save your friend's life by giving him this idea.
Try it yourself and share it with your friends!