Temperature Changes Cause Expansion and Contraction
Glass is made of atoms. These atoms move more with heat and less with cold. Faster moving atoms take up more space than slow ones. This is why your windshield or other auto glass expands in the summer and contracts in the winter.
Expansion and Contraction Exacerbates Windshield Damage
If you have minor damage on your windshield, don't be surprised if the minor damage quickly becomes major damage in Michigan's frigid winter. Chips, cracks, and other damage can quickly spread across weakened and compromised glass.
Heat and Frozen Glass
When you are in a hurry to get somewhere, and your windows are fogged up, you might be tempted to blast hot air on your frozen windshield. If the glass heats up too quickly on the inside and remains frozen on the outside, the atoms along the interior will move at different speeds than the exterior. The soundness of the glass will become compromised, and, bada-bing! ... you'll have a cracked windshield. Try starting your vehicle, setting the vents to blow toward the car interior, and allowing your windshield to heat slowly.
If you have ice on your windshield, pouring hot water on the frozen glass will have the same negative effect. If you must pour water on your windshield, use cold water.
Uh-Oh! Windshield Cracks
If you have already learned the hard way that temperature changes can have a negative impact on your auto glass, don't delay having your windshield replaced. Your windshield plays an important part in the structural integrity of your vehicle.