Warning: Things not to leave in your sub-zero car!
When the weather gets cold you know not to leave your water bottle, lipstick, the salad you brought for lunch, etc. in the car. But did you know that leaving your eyeglasses or sunglasses in a freezing car can destroy the lenses? When the temperature drops your lenses shrink, even just a fraction, and at a different rate than the coatings put on the lenses for scratch resistance and glare reduction. This causes "crazing", which looks like a dried up mudpuddle or ripples in the sand on the beach. Tiny microscopic cracks occur, sometimes not even visible, causing your lenses to feel smudged or dirty. Moral of the story: Don't leave your glasses or sunglasses in your car in extreme hot or cold temperatures! This morning it was 11 degrees; extreme!