Basically the title: If I leave the freezer door slightly open it seems to be “more frozen” than before – big chunks of ice on everything, stuff frozen together. Why is that? The food can go bad in this state but it LOOKS colder (I know this is stupid). In my mind it should just melt and warm up 🤷🏻♀️
In: Physics
It’s not colder or more frozen, leaving the door open just lets in warm, moist air from the outside, which condenses on the freezer’s contents and forms lots of frost and ice.
We cannot observe cold directly. What you can see is ice. Ice is formed when water freezes, so there must be water present. When you open the freezer there are warm water particles in the air that move into the freezer, meet the cold air and other objects, and then freezes, being removed from the air and sticking to the surfaces. So, while it isn’t actually getting colder, and instead getting warmer somewhat, the visible indicators of coldness are becoming more apparent.
If you left the door open long enough, you would notice it starting to thaw.
The freezer is so cold normally that being open doesn’t raise the temperature enough to get above 0 Celsius. What you’re seeing is all of the water in the air freezing and building up on surfaces. This doesn’t happen as much when it’s totally closed because it can only solidify the water that was already in the freezer cavity, at which point the air is completely dry. But if the door is slightly open, new wet air can get in and lead to more ice.
the ice is coming form the air outside coming in, cooling down inside the fridge, and water vapor in the air condenses out onto surfaces and freezes.
Your freezer is less efficient in like this as the ice effectively *insulates* the rest of the freezer, so overall its warmer than it “should” be.
Humidity in the air means condensation forms on all the cold surfaces, which then freezes into frost.
The humidity in the air is what makes frost on things, the more air leaking in, the more frost condenses from the moisture in that air, up to the point where the freezer can no longer keep the temperature below freezing.
You’re definitely making the freezer work harder and introducing warm spots, and if it’s running continuously, then it’s also leaking enough to be warmer overall than it’s supposed to be.
You’ve allowed water vapour to enter, it turns to ice when heat is extracted from it. Ice not only indicates low temperatures, but the presence of water.
A freezer getting colder will not create any more ice. If it’s below freezing already, all the water vapour will be ice.
Fun fact, the way you just assumed it was colder just because there was more ice (frozen water) in it, is exactly the same reason for sodium lauryl sulfates in things like toothpaste and soaps. The bubbles that form make the everyday person think it’s working better, when in fact it might even be working less effectively.
Water does not freeze instantly. And ice can be a good insulator. When you put something in the freezer the temperature goes down to almost 0 quickly but then stays there for a long time until it is frozen solid and the drops below 0.
Also if you put a large roast in the freezer it then can warm everything else in there until it is solid and then cool further down.
A tidbit I didn’t see anyone explain, is that cold air holds very little moisture, so normally the inside of the freezer would be essentially dry, any moisture that was in there having frozen at some point.
Then, when you let warm air in, there’s a whole new load of moisture that gets to freeze, therefore more ice.
(This next bit is more of an assumption)
While it’s open, the freezer is still trying to run, so ice may form as the air gets cold, then the cold air gets replaced by warmer air, and it just kinda continues until the freezer cant keep up anymore.
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