cold

[Immi666]

when my dad put my drinks bottle in the freezer the night before picnics and stuff, he always said to leave loads of space cos the ice is bigger than the water. so if water gets bigger when its cold, why do your fingers get smaller?

[WaldoMcFroog]

Are your fingers made of water then? ;-)

Water expands by about 9% upon freezing, if I recall my schoolboy physics lessons correctly, so your dad is right to ensure the bottle isn't over-filled.

I don't know the exact biological reasons why fingers contract, but when it is cold, the body withdraws blood from the extremities in order to ensure the abdomen is kept warm, and it does that because that's where the major organs are, so perhaps that's why.

[rsd2525]

i remember cross country runs in winter, everything gets smaller when cold !!

[kleedham]

Water only starts to expand as it approaches freezing point - it is the only liquid that does this. Your fingers, however cold they feel, will not be getting anywhere near freezing point. Plus as the last guy said, acute cold stimulates constriction of your blood supply to minimise loss of heat.

[Gef]

Water expands below 4C. If the internal temperature of your fingers drops to 4C you are in serious trouble.

[entropy]

when you get cold the body starts "peripheral shutdown", where the blood is reduced to your extremities and moved to vital organs. This causes your hands to shrink slightly. The reverse happens in hot temps; blood is sent to the extrmities to cool down....