DAY 11 - Stormy weather

The weather continues to deteriorate tonight as more storms move in. That factor makes it an easy segue to the rain-sensing wipers on the BMW. These are standard equipment on the 335i, which was a bit of a surprise to me when I found out I had them. Since then, I've been wondering how they work. I found the following explanation at the JDPower website.

The technology behind rain-sensing wipers is not complicated. A small area of the front windshield glass (usually located on the outside of the vehicle, opposite the rear-view mirror) is monitored by an optical sensor. The sensor is designed to project harmless infrared light at the windshield at an angle and then read the amount of light that is reflected back. A clean windshield will reflect nearly all of the light back, while a wet or dirty windshield will cause the light to scatter. The optical sensor can determine the necessary frequency and speed of the windshield wipers by monitoring the amount of light reflected back into the sensor.

As a safety precaution, and to prevent damage to the wiper mechanism, nearly all rain-sensing wipers must be activated each time they are used. The activation process prevents the system from automatically wiping a frozen windshield, or triggering while the vehicle is in a car wash; both instances could damage the blades or electric motor powering the wipers.

So, there you have it. Just in case you were wondering.