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Old 2007-01-08, 17:52   #1
mfgoode
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Question Bitter Winter.


Since those who are in the Northern Hemisphere are experiencing a bitter winter it would be interesting to know what the wintry conditions are in your part of the world such as the range of temperatures, clothing needed etc. etc.. I think the U.S. has had a tough time what with the hurricanes and tornados.
I hear that a huge junk of ice is floating south from the Northern parts of Europe.

So please let us know.

Here in Mumbai we are having cold weather (I would not call it a winter). At most the temp. drops to 16* C and reaches a high of about 29*C. Of course India is a large land mass and temp.s vary as one goes inland reaching 0* .
A common occurence when this happens is that water pipes burst due to the anomalous expansion of water.

However, more than the cold, our airports get fog bound and visibility is poor and below minima for a non instrument landing. This is the case with Delhi and recently Kolkatta. Flights have to be re scheduled for landing between say 5a.m. and 9 a.m. after which, due to the heating effect, the fog begins to lift as the sun rises.

Well up in the north, Kashmir freezes to sub zero temps. A picture in the TOI showed a boatman breaking the layer of ice that has formed.

A question worth pondering on is, why the lakes have a layer of ice on the surface but water below?

Any comments?

Mally
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Old 2007-01-08, 19:28   #2
ATH
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Denmark just had the warmest autumn and 2006 was the warmest year since measurements began in 1874.

We don't have any winter yet, in december and now in january temperatures are 5-10º C (41-50º F) and now its raining alot since new year. Normally we have like between -10ºC and 0ºC (14-32º F) and snow.
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Old 2007-01-08, 21:37   #3
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Quote:
Originally Posted by mfgoode View Post

Since those who are in the Northern Hemisphere are experiencing a bitter winter it
The UK has so far had the warmest winter in several centuries. In Cambridge we didn't get the first frost until November 2nd. More typical would be late September. We've had no snow at all yet; normally we'd have had at least 2 or 3 showers, though usually only a light dusting.

Our sage bush was in flower a month ago. Several Nicotiana glauca seedlings are still alive out of doors, even though they are not frost hardy. A geranium on our front doorstep has one flower head fully open and another with buds almost opening. Geranium plants are very barely hardy. We're still seeing blubottles around. There are reports of bunblebees flying around Cambridge on Xmas day. Both species are normally hibernating this time of year.


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Old 2007-01-09, 00:36   #4
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Quote:
Originally Posted by mfgoode View Post

Since those who are in the Northern Hemisphere are experiencing a bitter winter it would be interesting to know what the wintry conditions are in your part of the world...
Here in Arkansas, it is most certainly NOT bitterly cold. A light jacket is helpful, but if what you need is nearby, jackets aren´t even necessary. I have a feeling we´ll be well into February before I decide to take a jacket to work.
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Old 2007-01-09, 02:04   #5
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Quote:
Originally Posted by mfgoode View Post
A question worth pondering on is, why the lakes have a layer of ice on the surface but water below?
From NOAA (U.S. National Oceanic & Atmospheric Administration):
Quote:
Why does ice float?
We first have to account for the fact that ice floats on water at all, since ice is one of very few substances where the solid is less dense than its molten form. This is because the structure of normal ice, called ice I, is an open hexagonal structure. Each oxygen atom is at the centre of a tetrahedron with four other O atoms at the apices. The O atoms are concentrated close to a series of parallel planes that are known as the basal planes. The principal axis, or c-axis, of the crystal unit cell lies perpendicular to the basal plane. The whole structure looks much like a beehive, composed of layers of slightly crumpled hexagons. The net of O atoms is held together by hydrogen bonds. The H atoms lie along these bonds. It is the length of the hydrogen bond that creates the open structure of ice; when ice melts, some of the bonds are broken, causing a disordered structure with a higher density. But even in liquid water some short-range order remains, with a few water molecules retaining the crystal-like bonded structure until this is destroyed by thermal motion; this causes a curious density behaviour in fresh water, where there is a maximum density at 4°C.

Cooling the water down
Consider a fresh water body being cooled from above, for instance a lake at the end of summer experiencing subzero air temperatures. As the water cools the density increases so the surface water sinks, to be replaced by warmer water from below, which is in its turn cooled. This creates a pattern of convection through which the whole water body gradually cools. When the temperature reaches 4°C, the lake reaches its maximum density. Further cooling results in the colder water becoming less dense and staying at the surface. This thin cold layer can then be rapidly cooled down to the freezing point, and ice can form on the surface even though the temperature of the underlying water may still be close to 4°C. Thus a lake can experience ice formation while considerable heat still remains in the deeper parts.
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Old 2007-01-09, 06:19   #6
mfgoode
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Quote:
Originally Posted by sdbardwick View Post

Thank you for your excellent URL and your clarification of the structure of water molecules at freezing temps.

I think an important point to note is that with increased salinity, as in sea water, the freezing pont decreases to a lower temp and hence sea water in most parts of the oceans does not easily freeze. The exceptions are at the poles where the temps go below -23 * C which if I remember correctly is the freezing point of salt water.

Mally
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Old 2007-01-09, 14:19   #7
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Quote:
Originally Posted by mfgoode View Post
I think an important point to note is that with increased salinity, as in sea water, the freezing pont decreases to a lower temp and hence sea water in most parts of the oceans does not easily freeze. The exceptions are at the poles where the temps go below -23 * C which if I remember correctly is the freezing point of salt water.
The NOAA article says that typical seawater freezes at -1.8 C. My understanding of the mechanism that inhibits seawater freezing -from reading the article- is that it is due to convection in the salt water column. This occurs in salt water because salt water does NOT have maximum density at 4C, colder salt water is always denser. Convection brings heat to the surface which acts to keep the surface temperature above freezing point.
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Old 2007-01-09, 15:57   #8
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Red face Freezing of sea water

Quote:
Originally Posted by Richard Cameron View Post
The NOAA article says that typical seawater freezes at -1.8 C. My understanding of the mechanism that inhibits seawater freezing -from reading the article- is that it is due to convection in the salt water column. This occurs in salt water because salt water does NOT have maximum density at 4C, colder salt water is always denser. Convection brings heat to the surface which acts to keep the surface temperature above freezing point.
:surprised
Thank you for the correction Richard. C. I wonder what freezes at -23 but I wont hazard a guess nor check with google as it is irrelevant.
I must say the URL is a scholarly work.
As we are on this topic of weather you may be interested to read about the weird weather that Nature is capable of serving out.

http://www.livescience.com/forcesofn...eather-10.html

Mally
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Old 2007-01-10, 15:10   #9
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Quote:
Originally Posted by xilman View Post
The UK has so far had the warmest winter in several centuries.
Warmest winter in Finland since modern records began. Now snow at Christmas except for Northern Lappland. Most of December was 10C warmer than normal in Moscow too. China has just completed its warmest year in over 50 years too.

Where does the OP get his utterly incorrect information from? Don't answer that, I just don't want to know.
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Old 2007-01-10, 16:17   #10
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Cool Incorrect Information!

Quote:
Originally Posted by fatphil View Post
Warmest winter in Finland since modern records began. Now snow at Christmas except for Northern Lappland. Most of December was 10C warmer than normal in Moscow too. China has just completed its warmest year in over 50 years too.

Where does the OP get his utterly incorrect information from? Don't answer that, I just don't want to know.


Well you better hear it from the horse's mouth. The issue is not whether you had a warmer year ( particularly winter) or not since last year or a hundred years! Kindly get that in your head or LAPP. Just because Xilman says so does not follow that you should follow suit like sheep after the heardsman- all of you.
I c&p my original thread for you and it clearly shows that you, including Xilman, alias Leyland , cannot read simple English.

QUOTE:
"Since those who are in the Northern Hemisphere are experiencing a bitter winter it would be interesting to know what the wintry conditions are in your part of the world such as the range of temperatures, clothing needed etc. etc.. I think the U.S. has had a tough time what with the hurricanes and tornados.
I hear that a huge junk of ice is floating south from the Northern parts of Europe." UNQUOTE:

Winters In Europe are always bitter regardless of the higher temp this year. This is in comparison to my city Mumbai with reference to the context. Imagine me going out of my airconditioned cooled home in just a cotton shirt!
Well if you are true to your avatar (name) I suppose you have enough layers to keep out the cold.

It is well known that the winters have turned warmer this year due to the global warming of the entire planet which is causing grave concern to environmentalists. However that does not mean you are enjoying a few degrees higher. The fact is it is truly cold apart from a few sunny days. I have spent months in Moscow and always enjoyed the winters there as I was well equipped. It was mandatory to only put on our jackets when the temp was 17* or lower.

If you regard my Thread as ill informed Im sorry, but it is people like you and your hair brained comments that is causing all the trouble in the world now, right across the Western world who are suffering from Xenophobia and living in fear.

Well Im not happy with this situation and am a passive observer and follow the footsteps of My mahatma Gandhi-non violence

I put in my Thread with concern for you suff 'ing baskets and did not expect a complete turn around and betrayal for the sake of contradiction and ridicule.

Mally
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Old 2007-01-10, 16:28   #11
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Quote:
If you regard my Thread as ill informed Im sorry, but it is people like you and your hair brained comments that is causing all the trouble in the world now, right across the Western world who are suffering from Xenophobia and living in fear.
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