Why is it that water freezes on the surface of a lake but not below it?

More space = less dense, so ice is less dense than water. The water at the very top of the lake is in direct contact with the cold air, so it freezes first. And because ice is less dense than water, the sheet of ice doesn’t sink.

Why do rivers freeze differently than lakes?

The formation of ice in rivers is more complex than in lakes, largely because of the effects of water velocity and turbulence. Once the water temperature drops to the freezing point and further cooling occurs, the water temperature will actually fall below freezing—a phenomenon known as supercooling.

Why does flowing water not freeze?

For flowing water to freeze, the surrounding air has to be colder than 32°F, because the flowing water mixes with itself. So, the colder water on the surface mixes with the warmer water from the bottom, and the average temperature is somewhere between the two.

Can a whole river freeze?

Large rivers do not freeze “through out” because, Water, ice, and snow are good insulators and poor conductors of heat. The portions of a lake or river that are exposed to the cold winter air will freeze into ice and this ice insulates the water below from further rapid freezing.

How long does it take for flowing water to freeze?

So, how long does it take for water to freeze? In a freezer, it will take from 1 hour to two hours if you what to get ice cubes at a temperature of 0° F. If your water is cold or really hot, the water will freeze even faster (around 45 minutes).

Why does water freeze at the surface of a lake?

Explanation: In order for water to freeze, it must reach a temperature of 0oC. This occurs at the surface of a lake, which is why it freezes. However, water, being a special molecule, expands when it freezes, rather than contracts, meaning that the ice on top of the lake is less dense than the water underneath it.

What happens to the water at the bottom of a lake?

When water at some temperature higher than this is cooled from above, the cold water at the top settles to the bottom, letting warmer water get cooled. Once the temperature hits 4 degrees, though, this changes. The cold water stays on top and selectively gets cooled, until it forms ice.

What happens when water freezes in a puddle?

In calm water, such as a puddle, lake or ice cube tray, the process is relatively simple. As the water gets cold, it becomes denser and sinks in the water column. Just before it freezes, it becomes less dense and rises to the surface where it becomes solid.

Can a river freeze up from the bottom up?

Now, some sections of a river can freeze from the bottom up. Ice may form on the rocks which are underwater even though the surface of the river may not freeze; this type of ice is called anchor ice. Not much is known about anchor ice formation, growth, and detachment except that it forms in early winter on…