Fun Things to do When it's Cold Outside
Outdoors things that is, not rearranging your cupboards.
Make an ice-light - A Finnish traditionRequirements - bucket, water, candle.
Fill a bucket of water and leave it outside to freeze. I did this one when it wasn't so cold, just a few degrees below freezing, the actual temperature isn't so important as long as it consistently below zero so it doesn't start to melt.
Depending on the temperature, turn the bucket upside down and get the ice out. After a couple of days mine had about a 10cm / 4" slab of ice on the top and walls of around 2" / 5cm thick, there was a still liquid water bit in the middle at the bottom (so be careful when you tip the bucket upside down) which makes a space for the candle. The speed of freezing depends on your temperature of course, if it's well below freezing it might just take a few hours.
I supported the sides on a couple of pieces of wood around 2cm / 3/4" thick to allow for a flow of air to the candle. Light the candle, carefully place the ice on top and you've a beautiful icy light. The heat of the candle melts a hole through the ice above it after a while, but this doesn't seem to matter, the candle should be sufficiently protected by the ice walls from the wind to not blow out.
You could also try mixing some food dye in with the water to get coloured ones too or maybe use a glow stick or two as a light source instead.
Throw hot water into the air and watch it drift away as steamIt needs to be much colder for this one, it works better the nearer to boiling the water is and the bigger the difference between the hot water and the air temperature is. Try it on the coldest day you can and do what you can to keep the water as hot as possible, realistically it needs to be below around -20°C for good results. The colder it is the better and easier.
Get a vacuum flask and fill it with boiling water (take care) leave for a minute or so, pour it away and fill again with boiling water, put on the lid and go outside, you'll also need a plastic cup or even better an insulated mug.
Pour some of the water into the cup and throw it into the air. Marvel at how the hot water goes up but then turns to steam and simply drifts away! There's lots of opportunity for photography too, get into position with a plain background behind where the steam will be and play around with shots into the sun or lit by the sun from the front.
If it's very cold and you're very careful, you could even try to put some in a supersoaker, water pistol or similar and puff out steam.
In a similar vein try blowing bubbles and watch them freeze into ice crystal balloons before they land (or maybe shortly afterwards)
Expanding ice and bottlesA simple one but fun for the younger ones or if you've never done it before.
On a cold night / day fill a bottle with cold water and screw the lid on tight, place it outside and wait a few hours or until the next day. As the ice freezes it expands and so will split or break the bottle. It looks better with a glass bottle as it's more obvious what has happened, though of course you then have broken glass to clean up (easier if you can leave it until the ice has melted) or place it on a tray first. Plastic bottles might just expand with the ice and not split.
Leave the top off the bottle but fill it right to the very brim, you should get a column of ice coming out of the top of the bottle.
Drill a hole in the bottle top or saw a slit, with some experimentation you can make some cool shaped ice extrusions.
SupercoolingIf you have more time and/or patience, you could try supercooling water.
The idea is that you can cool a liquid below its freezing point and as long as it is clean and undisturbed it won't freeze for a while despite being cold enough to. When it does freeze, it does so very quickly.
You could try this using your freezer but there's a lot of potential for messiness that is more easily contained outdoors.
Take several clean plastic bottles and fill them with water, screw on the lids and leave them outdoors in a calm spot where it is below freezing. As a guideline for a 500ml / 1 pint bottle, 3 hours at -20°F (the temperature of most freezers) is the right sort of time but it's very variable. Some of the bottles may have already frozen solid (and so split - hence this is better outdoors) but hopefully some should still be liquid and supercooled.
Carefully pick one of the still liquid ones up and either tap the side sharply, tilt upside down or shake it gently. If you're lucky and it is supercooled you will see the liquid water turn to ice starting within a matter of seconds and spreading throughout the bottle.
Another variation is to very carefully unscrew the top from the bottle and pour it onto a very cold hard surface (should be lots around if you're outdoors!). This time if you're lucky, you will make a mound of ice as the water comes out liquid but almost immediately freezes as it hits the already frozen surface, make sure there is already a small piece of ice that you're pouring it onto.
Ok, I admit this one didn't turn out to be that much fun when I tried it, but it did work and can lead to some useful practice calculations (assuming you consider calculation practice to be useful). I have seen reference to it elsewhere sometimes accompanied by misleading pictures, see the calculations for how you can tell this.
The idea is that you blow some balloons up indoors where it's warm and mark them by drawing something on them. Being of a scientific persuasion I drew some lines with a ruler and marked them at 1, 2, 5,10 and 20 cm points (or thereabouts). They are then placed somewhere cold, I put them in my freezer as a trial rather than outside as it wasn't so cold there. The air will occupy a smaller volume when cold and the balloons will shrink. Several hours later I took them out and measured the lines I had drawn to see how much they had shrunk. The answer was not much, so back they went, and again, and again. They definitely had shrunk as when I first put them in it was a bit of a squeeze, when they'd cooled down they were loose in their position. My room temp was 20C, freezer temp -20C, a 40C difference.
The 20cm (200mm) line on the yellow balloon shrank down to 194mm, yes that's a 6mm reduction (I did warn you).
194mm from 200mm is a shrink ratio of 194/200 = 0.97
That's one dimension and we can assume the ratio of the other 2 in the volume are proportionally the same, so the volume shrank by a factor of 0.97 x 0.97 x 0.97 = 0.91
The volume of air is proportional to its temperature (Charles Law) this table shows a ratio of 0.99 : 0.86 of +20C to -20C air or an expected reduction in volume to 0.99/0.86 = 0.87
Which is in the ball park of my measured 0.91, I had a 9% reduction compared to a theoretical 13%.
To get exactly 0.87 would give a linear shrinkage of the cube root of 0.87 or 0.87^1/3 = 0.95 (converting from volume change to linear change)
My 200mm line would have shrunk to 200 x 0.95 = 190mm, 4mm off from what I got.
If you investigate this online you may encounter some apparently far more shrunken balloons than this in the same circumstances, they have mainly just deflated. The test is to bring them back into the house to warm up again when the length of the line you have drawn should return to its original value.