2 ms·
Surprised the bottom of the iceberg crumbled so easily (like sand) at 4m 16s: https://www.youtube.com/watch?v=UufMqwyO7pY&t=4m16s https://www.youtube.com/watch?
by nomilk 2mo ago
Surprised the bottom of the iceberg crumbled so easily (like sand) at 4m 16s: https://www.youtube.com/watch?v=UufMqwyO7pY&t=4m16s https://www.youtube.com/watch?v=UufMqwyO7pY&t=4m16s
I'd have assumed it would be colder and more compacted (being toward the bottom and further under water), and therefore harder.
- FromHoiPolloi 2mo agoMy take would be that underwater temps cannot get below freezing. So the surrounding temperatures above water can be lower than under water.
- nh23423fefe 2mo agoplus thermal conductivity of water vs atmosphere
- mrloopex 2mo agoFreezing point of water changes with salinity and impurities. By definition a liquid cannot be below its freezing point until it has completed its phase change.
- FromHoiPolloi 2mo agoYes. My point was that it's easier(?) to get below freezing point above water than below. So while the cold air keeps the upper part of the iceberg (relatively) intact - it will slowly melt below the sea until the center of gravity changes enough to flip over.
- RetroTechie 2mo ago> By definition a liquid cannot be below its freezing point until it has completed its phase change. Supercooled water is a thing: (and I've seen it a few times myself) https://en.wikipedia.org/wiki/Supercooling https://en.wikipedia.org/wiki/Supercooling
- wahern 2mo agoSuperheating, too, and that's something that can happen in a microwave, occasionally causing severe burns when superheated water flash boils. AFAIU, it's the same phenomenon--lack of nucleation sites to kick-off the phase transition.
- mrloopex 2mo agoDoes that mean every TTT diagram is wrong? Nevermind I just learned about CCT diagrams. I guess having only one year of materials engineering means I should STFU. :)
- Pooge 2mo ago> My take would be that underwater temps cannot get below freezing Yep, density of water changes with temperature—it's the only thing that has that phenomenon—and therefore the colder water is always at the surface. That's actually what made life possible since life could survive despite a frozen surface. Happy to be proven wrong, but that's what I learnt making cocktails and investigating clear ice :)
- dotancohen 2mo agoLots of things change density when temperature changes. Water is unique that below 4°C, it gets less dense as it cools - and that trend continues even through the phase change. That's why, as you mention, ice floats, and the surface freezes first, and fish can live below a frozen surface.
- Pooge 2mo ago> it gets less dense as it cools Right!! Thanks for correcting me.
- amszmidt 2mo agoHow cold is cold? :-) Water below ”sea” level tends to stay around -1C (salt water) to 4C. Below that, water becomes ice… Ambient temperature can drop to -40C … internally these ice blocks hoover around -10C.
- brianpan 2mo agoThere are different ways to create an iceberg. You are probably thinking of a hard chunk of ice breaking off into the ocean, but probably a more common way is glaciers running into the ocean. A glacier is basically a "river" of snow and ice slowly flowing down a mountain. It would generally not be very compacted. Fun fact: smaller chunks (less than 15m) are called "bergy bits".