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250 votes
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Strange ice found in my garden

Congratulations, you found an inverted pyramid ice spike, sometimes called an ice vase! The Bally-Dorsey model of how it happens is that first the surface of the water freezes, sealing off the water ...
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222 votes

Why does ice cream get harder when colder?

A couple of decades ago I was peripherally involved with some research on the properties of ice cream being done by the company Walls in the UK. The work was on relating the consistency of the ice ...
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91 votes
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Why was water freezing almost instantaneously when shaking a bottle that spent the night outside during a frosty night?

Congratulations, it sounds to me like you've just observed supercooled water! There are many videos on YouTube that describe this phenomenon, and explain it much better than I could, see here for a ...
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68 votes
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Does the sea level increase if an iceberg melts?

The Archimedes principle says that a floating body will displace an amount of fluid that is equal to its weight. Since the iceberg floats, it weighs the same as the water it displaces. If it had the ...
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64 votes
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Why does ice melting not change the water level in a container?

Good question. Assume we have one cube of ice in a glass of water. The ice displaces some of that water, raising the height of the water by an amount we will call $h$. Archimedes' principle states ...
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62 votes
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Why does water rise through a hole in ice

Suppoose you put an ice cube into water, then it's going to float with about 92% of it underwater. This is shown in diagram (a) below: But now suppose I make my ice cube a different shape. I'm going ...
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62 votes
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Why is the air inside an igloo warmer than its outside?

An igloo is not made from ice, but made from compressed snow. Snow is basically semi-frozen water or frozen crystalline water. Contrary to intuition, snow has actually got very good insulating ...
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54 votes

Why does ice melting not change the water level in a container?

Here is an explanation that needs no explicit equations. Consider the following diagram, in which part1 and part2 represent the ice. The displaced water volume equals part2 volume and has as much ...
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47 votes

Why do small patches of snow remain on the ground many days or weeks after all the other snow has melted?

A hidden assumption is that all of your remnant piles start with the same amount of snow. However your first photo seems to be adjacent to, and parallel to, a roadway. You mention you’re in Boston, ...
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44 votes
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Why do my "steel ice cubes" have water in them?

Water thaws at 0°C. The latent heat of fusion of water is $L_i = 344000$ J/kg, which means that to thaw the frozen water inside your cubes requires much, much more energy than you're accounting for. ...
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42 votes

Does the sea level increase if an iceberg melts?

The one you're not contemplating: that the sea level rises because of melting of ice that's currently over land. As noted in Rodrigo's answer, when sea ice melts there is no change in the water level, ...
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29 votes

Why is ice made from boiled water clear?

I'm really winging this one because the last time I did an equilibrium calculation was 35 years ago! But I'm fairly sure of a partial answer (see discussion at end). A gas's solubility in water (or ...
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29 votes
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Why is ice made from boiled water clear?

The short answer: Cloudy ice is caused by gases (mainly nitrogen and oxygen) dissolved in the water that come out of solution when the water freezes. The small bubbles trapped in the ice cause the ...
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28 votes
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Why does ice make such peculiar sounds?

The pitch of the sounds start high and end up low. Is this some kind of doppler effect? No. This is chirp induced by dispersion, which is the acoustic version of the same phenomenon for light. This ...
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28 votes
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How does a river freeze when the water keeps moving?

You know that ice is less dense than water. Then, water that freezes will stay at the surface. Also, take in mind that water will only freeze on the surface. Then as you said, any ice that forms will ...
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26 votes

How does a river freeze when the water keeps moving?

The river does not freeze in its moving parts. It begins to freeze from the banks in places where the water is motionless or nearly so. Then the frozen area gradually grows towards the center of the ...
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25 votes
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Why are some parts of this ice block cloudy and other parts clear?

As @pr1268 explained, tap water is not pure: it contains dissolved gases (basically air) and dissolved minerals. However, I do not think stratification causes this phenomenon: I think that as long as ...
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23 votes
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Frost bubble formation

I think this is a frost flower, crystallofolia, closely related to hair ice. They can appear quite similar to the above photos. Pluchea odorata — Marsh Fleabane — Mown Stem on Path December 25,...
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23 votes

Is there a temperature at which ice is denser than water?

Ice can be denser than water for certain values of $P,T$. Look at these two pictures taken from here: The darker areas in the second picture denotes areas of greater density. So you can clearly see ...
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23 votes
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Why are snowflakes flat?

The most comprehensive, rigorous work I have ever seen on snowflake formation is Dr. Kenneth Libbrecht's (free) book Snow Crystals (I've linked to its location on the Arxiv). This answer will pull ...
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20 votes
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Why is ice more reflective than liquid water?

In fact ice is slightly less reflective than water. The reflectivity is related to the refractive index (in a rather complicated way) and the refractive index of ice is 1.31 while the refractive index ...
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20 votes

Why is the air inside an igloo warmer than its outside?

Although igloos are often associated with all Inuit and Eskimo peoples, they were traditionally used only by the people of Canada's Central Arctic and Greenland's Thule area. Other Inuit tended to use ...
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20 votes

Why do small patches of snow remain on the ground many days or weeks after all the other snow has melted?

I doubt that there is a single reason. Many particular combinations of factors may result in differences between the melting rate and the quantity left over at some time (which depends on both melting ...
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18 votes

Why does water rise through a hole in ice

I don't think John's explanation is sufficient. If 3 feet (90 cm) of ice is floating, it should leave about 7 cm of gap (according to the 92% number) - that is not what was described in the question, ...
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17 votes
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Does the shape of ice affect the amount of heat required to melt it

It's approximately the same energy to melt little chips of ice and one big one, but not exactly because there is energy involved in creating surfaces, called the "surface energy" (or surface tension). ...
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14 votes

Why are some parts of this ice block cloudy and other parts clear?

The cloudiness is caused by dissolved air bubbles. Plus, tap water is notoriously rich in mineral particles (giving nucleation sites). Seeing how you placed the tap water in the freezer, the cold ...
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  • 1,481
13 votes
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Why does an ice-cube turn faster and faster while melting in water?

The same physics that explains why water tends to rotate when you drain your bathtub also answers this question. In both situations there is a downward flow of water that accentuates the residual ...
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  • 5,555
12 votes

What's the best (practical!) shape to maximize the rate of heat transfer?

The more surface area, the more heat transfer. Ideally you'd use a single-molecule sheet, but that's impractical. Practically, using crushed ice is very simple and very effective. You could also ...
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