what causes condensation on the inside of windows, particularly when it’s warmer inside and cooler outside?



what causes condensation on the inside of windows, particularly when it’s warmer inside and cooler outside?

In: Chemistry

The cooler air on one side cools the glass of the window. The cool glass attracts the moisture in the warm air until there is enough of it to condense

Literally just that. Condensation collects on the warmer side. Think of an extremely cold drink. Condensation is on the warmer side. It’s sucking moisture right out of the air.

It’s important that you specified “warner inside and cooler outside” because that temperature differential is a major key factor in the presence of condensation.

Condensation occurs when warm air collides with cold surfaces, or when there’s too much humidity in your home. When this moisture-packed warm air comes into contact with a chilly surface, it cools down quickly and releases the water, which turns into liquid droplets on the cold surface.

There are three important factors that cause condensation:

The level of moisture in the air.
The temperature of the air in your home/car/other side of the window.
The surface temperature of the windows.

The more moisture in the air the more likely it is that you will get condensation.

Condensation in the atmosphere usually occurs as a parcel of rising air expands and cools to the point where some of the water vapor molecules clump together faster than they are torn apart from their thermal energy. That kind of condensation is how clouds are formed; water vapor in the air condensing into water droplets which are suspended in the atmosphere in big fluffy white pockets, aka clouds.

Ever heard the term “relative humidity,” or a humidity expressed as a percentage? “It’s 80 degrees today, with the humidity up around 70%,” etc.

Turns out, there is a maximum amount of moisture that air can hold. Also, turns out that warm air can hold more moisture than cool air. So, the air *inside* your warm room is holding some amount of moisture that it can comfortably hold (so, it’s not raining in your room), but when it comes into contact with the cold window pane, that same amount of moisture now exceeds the capacity of the cooled air. The excess comes out of the air as liquid water.