Does water freeze from the top down?

Answer 1

Water does not only freeze on the top. Given cold enough temperatures for a long enough period of time it would freeze to the bottom. Instead it freezes from the top down. Water freezes on from the top down because ice is less dense than water (H2O). As ice crystals form they rise to the surface.

Demonstration:

• Get an ice cube and a glass of water.
• Try to push the ice to the bottom.
• Let go.

See! Ice IS less dense than water!

Some may say that ice is lighter than water, but that's not the whole story! Mass does matter, but so does volume when discussing why objects float.

The density of a substance is found by diving its mass by its volume (the space it takes up). For the space that it takes up, ice has less mass than the liquid water that would fill the same space.

The fact that solid H2O is less dense than liquid H2O is one of the many reasons why water is so unique. No other common substances and very few (if any) uncommon substances have this property. In most matter, the particles are more tightly packed in solid form than in liquid. For crystalline solids, the particles are also more organized in this form. However, water's chemical properties and hydrogen bonds make it more organized but less dense when it is in a solid form. This is because the particles become organized in such a way that there is more empty space between them. This empty space does not contribute to the mass, but it does cause the water to expand.

Demonstration:

• Fill a plastic bottle with water.
• Securely close the lid.
• Place the bottle in the freezer over night.
• Has the shape of the bottle changed? Why?

Answer 2

Most liquids freeze bottom upwards. This is because the colder liquid is denser, so the portion which freezes is lower down, hence bottom upwards. Conversely, the warmer portion rises and thus the higher part is last to freeze completely.

Answer 3

Sort of. Ice is lighter than water and tends to float. Also, in most natural situations, the atmosphere (in contact with the "top" of a body of water) is colder than the ground underneath the water.

In a freezer where the water is surrounded on all sides by equally cold air, the water freezes from the outside in... top, bottom, sides before the middle.

Answer 4

The top water is always miserable, so when it freezes first, it leaves its life of misery quicker than the bottom water.

Answer 5

Lakes would freeze solid and perhaps kill the fish (unless they adapted to being frozen).

Answer 6

snow melts from the bottom up because heat from the earth rises and melts the snow

beneath and works its way up

Answer 7

I believe they don't.