Buzz
In fact, it does freeze! But this happens only in places where the temperatures are incredibly low, like in the Arctic or Antarctica. Water is made up of minuscule molecules (MOL-uh-kyools) that move constantly. When it gets colder, these molecules slow down. At 32°F (Fahrenheit), they gather together and form ice crystals.
Ocean water is distinct from fresh water found in lakes, rivers, and ponds. It contains dissolved salt, which consists of tiny particles called ions. These ions surround the water molecules and prevent them from clumping together to form ice. The ocean’s water won’t freeze until it reaches around 29°F.
As seawater cools, it becomes denser, causing the molecules to pack more tightly. This dense water sinks, leaving the less salty water on top. Eventually, this top layer begins to freeze. The ice formed from seawater contains very little salt. In fact, if you melt it, it’s drinkable!
In extremely cold regions, like the North and South Poles, there’s a lot of sea ice at the surface, especially during winter. However, this doesn’t mean the entire ocean is frozen. Below the ice, the ocean remains liquid. If it weren’t, animals like seals, fish, and polar bears in the Arctic or penguins in Antarctica wouldn’t be able to swim or dive beneath the frozen surface to hunt.
Each year, more and more sea ice melts. To understand why this is so crucial, check out this Discovery video on disappearing penguins.
