Why Do Windshields Fog Up?

Have you ever experienced driving on a road with your windshield slowly fogging up? This is both a scary and alarming situation, especially if you’re driving at highway speed. The fogging can happen within minutes after you hit the road. What causes fogging and what can you do to prevent it?

Reasons for fogging

Most of the causes of windshield fogging are environment-related. Here are some of the possible culprits you should be aware of:

Heat. When it’s warm, more moisture is present in the air. As the heat lingers, the water molecule turns to gas which causes the fog on your windshield.

Humidity. So far, this is the most common cause of fogging. What happens is that water becomes vapor. Since you are breathing, your body releases this vapor. This can stick to your windshield, much so if there are multiple people inside the vehicle.

Condensation. Have you ever experienced fogging early in the morning? This happens when warm air hits your cold windshield glass. Condensation is more prevalent during hotter days and you have your car’s air-conditioning unit running.

Surface tension. This happens when tiny water droplets bond together and form a layer which will turn out to be fog-like.

What to do with windshield fogging

Fogging will reduce the visibility of the road which, in turn, increases your risk to accidents. It’s important that you know what to do when your windshield fogs in the middle of a busy highway. There are many easy steps you can take including the following:

Let the water evaporate

If the fogging is caused by condensation, you can simply turn the heat on to defrost the molecules. It’s like drying your clothes, but in this case, it’s your windshield. Evaporation will be an optimal solution if you get to act upon the fog the moment it forms.

In case the fog is too thick for the heater to evaporate, get off the car and wipe it with a dry cloth. After that, turn the heat on and let the remaining fog evaporate until your windshield is clear again.

Let the air get dry

When the outdoor temperature is too cold, there’s a chance that your body will cause the formation of fog. In this case, you can simply turn the heater on a warm setting until the air becomes dry and the fog will melt away.

This is a very effective solution during the winter season. If this doesn’t work, you’ll have to wipe the haze manually before using the heater.

Crack your windows

Since your breath can cause the fog formation, you can simply crack your windows during warmer days. This is so the outdoor wind can balance the temperature inside, thus reducing the chances of having fog on your windshield. If you can, turn off the recirculation setting for a while and the fog should go away.

To successfully remove the fog, it’s best to let the outdoor air circulate inside. Forcing the indoor air circulating won’t fix the problem. If all else fail, a defroster should be the long-term solution.