isn't ice same in polar rivers and in ur refrigerator?

Question

when water in polar river's water freezes,the frozen upper layer doesn't allow the inner layers to freeze which protects the animals living in it.
similarly when water starts freezing in ice tray,the water freezes from the sides of the tray.
then why does water in ice tray freeze?doesn't the outer frozen layers prevent the whole water from freezing?

Answer 1

No.

Rivers or lakes have other sources of heat. Rivers have warm water flowing in all the time. Lakes have heat coming up from the ground beneath. Thus, the system comes to some equilibrium where there's frozen ice on top but liquid water below.

If there was no other source of heat then the rivers and lakes would slowly, eventually, freeze all the way down.

Similarly, in your ice tray, there's no source of heat. Eventually, they'll freeze all the way through.

Answer 2

Not exactly the same as there's other junk floating around in the polar river, but effectively the same.

In polar ice, the lower layers don't freeze either because (1) they're just too deep or (2) they have movement - currents - that limit the freezing. Even inland lakes in the U.S. see this - lakes will freeze at the top, but unless they're quite small it's unlikely the WHOLE lake will freeze top to bottom. In fact, that's how people are able to go ice fishing - they drill a hole through the ice layer - it's thick enough to support them, but doesn't go to the bottom. Then they fish for whatever's swimming below.

Your fridge, by comparison, is quite tiny, and most items placed in the freeze will freeze in entirety, if they are capable of freezing at all.

Answer 3

It is a matter of degrees. The ice on a northern river could reach feet thick. This is enough to prevent further freezing.

The ice in the ice cube tray is tenths of inches think and allows for enough heat to escape from the trapped water inside to cause it to freeze solid.

Answer 4

No not at all