You Know It's Cold When...

[sheeny]

We got some good rain on the weekend. Last night it fined up, so this morning I went out to check my rain gauge. We had a solid frost last night, it got down to -4 degrees C.

I was glad to find we'd had 28mm of rain (if it's going to be cloudy, the least it could do is rain and get it over and done with!;) ) but I was saddened to see that my rain gauge was "not happy, Jan!".

Global warming has a lot to answer for... if it had just snowed my rain gauge would still be healthy!:P

The following are macro and super macro shots taken with my Olympus C-5060WZ (handheld). Just as well I already have an entry in this month's photo challenge - it saves me having to consider any of these...

Al.

[asimov]

Yep! Thats certainly cold enough!

[Astroman]

ahhh you need a tipping bucket gauge :) WOW that looks damn cold.

[Volans]

For this warm blooded Queenslander, that is just too cold for anyone's own good!!

:cold:

Those are great shots Sheeny but they do raise a question. In the close ups of the ice block, there are cavaties. I'm assuming that these cavaties are made from pockets of air. :shrug:

If so, then how did they get preserved? Surely the water did not freeze instantly, which it would have to do in order to preserve the bubbles of air.

What is going on here? Why is it so?

BTW, if anyone tells me that atmospheric pressure does the work...:mad2: :poke:

:lol: :lol:

Peter.

[sheeny]

Volans, mate... no, it's not the atmospheric presure that does the work, "it gets in like liquid into chalk"!:rofl:

What I believe happens (anyone with a better understanding of chemistry and physics please feel free to correct me) is that air (i.e. the gases in the air) are soluble in water. The solubility increases with decreasing temperature (at least I'm sure this is the case with oxygen - that's how fish "breathe"!).

I would expect the water in the rain gauge to freeze from the outside in. In fact, you can see in the photos the white bulge where the last bit to freeze is. Once the surface is frozen, the gas can't escape so as the ice layer around the outside thickens the gas concentration in the remaining liquid water increases and it becomes supersaturated. When a jagged little bit of ice forms, a gas bubble forms on that, and then the water freezes around it and so on.

The last bit where the ice is white, is that colour for two reasons I think. Lots of tiny micro-bubbles of gas in the ice and fractures in the older ice where the freshly freezing ice is creating force to bend it... just so it can bust the side out of my rain gauge!:P

Al.

[Volans]

Thanks Al, your explanation makes sense. I did a search on Google and found out about Henry's Law regarding solubility of gasses in a liquid. Also found a neat site

http://joannenova.com.au/Demos/Icecastle/Icecastl.html

that pretty much says what you said.

Peter.

[sheeny]

You mean it really does "get in like liquid into chalk"???!!!

:rofl:

Al.