Winter 2010/11

[DirtyDozen12]

Can't have a winter thread without a viewing of this chap again 

Wow, that is an outrageous slip!!!!!!!!!!!  The poor hoor didnt even get his hands down to break his fall!!!!!!

[EC Unique]

Just trying to illustrate that warm water freezes quicker but I'd say the alcohol in cool water probably helps

Is this true or just an old wives tale? Is it a scientific fact that it takes water at 5 degrees longer to reach zero than water at 50 degrees?

I doubt it.

The hot water is more likely to be supercooled. This means that the hot water's temperature is more likely to cool to temperatures below zero degrees Celsius. In the cold non-supercooled water, ice crystals form and float to the top, forming a sheet of ice over the top of the water, creating an insulating layer between the cooler air and the water. This ice sheet also stops evaporation. In the hot water that has become supercooled (thus, no longer hot) the water, when it does freeze, freezes throughout, creating more or less of a slush before freezing solid.

Why is hot water more likely to be supercooled? Because hot water is less likely to contain tiny gas bubbles. Gas bubbles form from dissolved gasses as the water cools. When the hot water was heated, these dissolved gasses may have been driven out. In cold water, ice crystals use the tiny bubbles as starting points for formation (nucleation points). But in the hot water, there are no bubbles, so there aren't as many starting points for the ice crystals.

Thats me told 

[Gaaman]

After a Arctic start to the week it has really become quite mild, even warm in the mornings. At night it is still quite cold though.
I love the big roaring fire in winter time. No football training to be running it. First class.

[johnneycool]

After a Arctic start to the week it has really become quite mild, even warm in the mornings. At night it is still quite cold though.
I love the big roaring fire in winter time. No football training to be running it. First class.

So what's the most economical at the moment, coal or logs for my stove?

[David McKeown]

Just trying to illustrate that warm water freezes quicker but I'd say the alcohol in cool water probably helps

Is this true or just an old wives tale? Is it a scientific fact that it takes water at 5 degrees longer to reach zero than water at 50 degrees?

I doubt it.

The hot water is more likely to be supercooled. This means that the hot water's temperature is more likely to cool to temperatures below zero degrees Celsius. In the cold non-supercooled water, ice crystals form and float to the top, forming a sheet of ice over the top of the water, creating an insulating layer between the cooler air and the water. This ice sheet also stops evaporation. In the hot water that has become supercooled (thus, no longer hot) the water, when it does freeze, freezes throughout, creating more or less of a slush before freezing solid.

Why is hot water more likely to be supercooled? Because hot water is less likely to contain tiny gas bubbles. Gas bubbles form from dissolved gasses as the water cools. When the hot water was heated, these dissolved gasses may have been driven out. In cold water, ice crystals use the tiny bubbles as starting points for formation (nucleation points). But in the hot water, there are no bubbles, so there aren't as many starting points for the ice crystals.

Thats me told 

I'll have to bow to you on this one, all I know is thats its known as the mpemba effect and we did an experiment to show it in alevel physics with water at 35C and water at 5C.  The only reason for the experiment was the teacher wishing to prove we should use cooler water to defrost our windscreens

[Gaaman]

Heavy rain here for past few days. A lot of water lying on the road this morning. Couple more days of this and we could see some serious flooding like last November.

[muppet]

Just trying to illustrate that warm water freezes quicker but I'd say the alcohol in cool water probably helps

Is this true or just an old wives tale? Is it a scientific fact that it takes water at 5 degrees longer to reach zero than water at 50 degrees?

I doubt it.

The hot water is more likely to be supercooled. This means that the hot water's temperature is more likely to cool to temperatures below zero degrees Celsius. In the cold non-supercooled water, ice crystals form and float to the top, forming a sheet of ice over the top of the water, creating an insulating layer between the cooler air and the water. This ice sheet also stops evaporation. In the hot water that has become supercooled (thus, no longer hot) the water, when it does freeze, freezes throughout, creating more or less of a slush before freezing solid.

Why is hot water more likely to be supercooled? Because hot water is less likely to contain tiny gas bubbles. Gas bubbles form from dissolved gasses as the water cools. When the hot water was heated, these dissolved gasses may have been driven out. In cold water, ice crystals use the tiny bubbles as starting points for formation (nucleation points). But in the hot water, there are no bubbles, so there aren't as many starting points for the ice crystals.

Thats me told 

I'll have to bow to you on this one, all I know is thats its known as the mpemba effect and we did an experiment to show it in alevel physics with water at 35C and water at 5C.  The only reason for the experiment was the teacher wishing to prove we should use cooler water to defrost our windscreens

Does this explain the formation of hailstones in warmer climates/weather versus snow in colder ones?

[caughtredhanded]

After a Arctic start to the week it has really become quite mild, even warm in the mornings. At night it is still quite cold though.
I love the big roaring fire in winter time. No football training to be running it. First class.

So what's the most economical at the moment, coal or logs for my stove?

I use mostly logs but I always put a shallow layer of coal on top to put a 'crust' on the fire. I find a roaring fire is inefficient as most of the heat is going up the chimney. Best to keep a good heat ticking over and not consuming a pile of sticks.

[BarryBreensBandage]

Just trying to illustrate that warm water freezes quicker but I'd say the alcohol in cool water probably helps

Is this true or just an old wives tale? Is it a scientific fact that it takes water at 5 degrees longer to reach zero than water at 50 degrees?

I doubt it.

The hot water is more likely to be supercooled. This means that the hot water's temperature is more likely to cool to temperatures below zero degrees Celsius. In the cold non-supercooled water, ice crystals form and float to the top, forming a sheet of ice over the top of the water, creating an insulating layer between the cooler air and the water. This ice sheet also stops evaporation. In the hot water that has become supercooled (thus, no longer hot) the water, when it does freeze, freezes throughout, creating more or less of a slush before freezing solid.

Why is hot water more likely to be supercooled? Because hot water is less likely to contain tiny gas bubbles. Gas bubbles form from dissolved gasses as the water cools. When the hot water was heated, these dissolved gasses may have been driven out. In cold water, ice crystals use the tiny bubbles as starting points for formation (nucleation points). But in the hot water, there are no bubbles, so there aren't as many starting points for the ice crystals.

Thats me told 

I'll have to bow to you on this one, all I know is thats its known as the mpemba effect and we did an experiment to show it in alevel physics with water at 35C and water at 5C.  The only reason for the experiment was the teacher wishing to prove we should use cooler water to defrost our windscreens

Does this explain the formation of hailstones in warmer climates/weather versus snow in colder ones?

You are absolutely spot on fella.

The hailstones are raindrops that pass though a belt of air with a strong updraft. The water passing through this belt has to be supercooled to form hailstones. The more turbulence up there the bigger they are. Which is why thunder storms are ideal for hailstone formation.

And then the boyos become too big for the air pressure to hold them and they fall.

I need to get out more.

[BarryBreensBandage]

After a Arctic start to the week it has really become quite mild, even warm in the mornings. At night it is still quite cold though.
I love the big roaring fire in winter time. No football training to be running it. First class.

So what's the most economical at the moment, coal or logs for my stove?

I use mostly logs but I always put a shallow layer of coal on top to put a 'crust' on the fire. I find a roaring fire is inefficient as most of the heat is going up the chimney. Best to keep a good heat ticking over and not consuming a pile of sticks.

Here is a person that knows their fires.