Also, if one lives above or below a road, sirens and other traffic noises often vary with the time of day, etc. The standard explanation is diffraction, but maybe others have additional angles or insights to lend.

Following the recent spell of cold weather, I noticed that there are still piles of dirty snow with sand or grit (but not salt) in them, but all the clean snow has melted.

I was walking along a canal several days ago, and, the UK weather being what it is at the moment, the canal was frozen. However under all the bridges that crossed the canal, whether footbridge or road bridge, the water was unfrozen. What is it about the bridges that stops the water under them from freezing?

The cold snap we're experiencing in Britain at the moment has made me ponder this.  Answers from my friends and relations so far have included:

Because the water is moving (But how does this stop it from freezing?)

Because the water is under pressure

Because the temperature is above zero underground

Beacuse of the otters that the water companies keep swimming around in the pipes (I think this one was a joke)

So...why doesn't the water in the mains pipes freeze when it is below freezing point outside?

Having recently moved to Canada from the UK it struck me that everybody has to wear extra clothes to keep warm, but the caribou I saw the other day don't seem to notice the freezing temperatures. Animals that live in the Arctic for example are well adapted to their environment e.g. thick fur or layers of fat, but if humans had not invented clothes where on the planet would we be able to survive?

In the coldest parts of the world the temperature can be below -78 degrees C. which is the temperature at which carbon dioxide freezes. Would it be practical to remove the carbon dioxide from the atmosphere, at low cost, in these cold places, and so have a means of limiting the level of carbon dioxide in the the earth's atmophere?

Being a student of physics, reversal of magnetic poles of Earth has been quite a topic of concerned for me. But I didn't know that it's now shifting so fast.

The thing which I wanna know is, would this, shifting of magnetic poles of Earth, result in sun rising and setting from the opposite directions, I mean, after that Sun will rise from West and will set in East. I'm not very sure but what I've studied so far from that I think YES it would. Can anyone explain this?

Why is it that meteo radars don't detect low clouds like fog. Are they just looking up to avoid distractions or is there something in the fog that makes it invisible?