Guess which way Heathrow is from our place?

For some reason that I am still not quite sure about, the sky over London is much more prone to vapour trails than the sky over Melbourne. Is it becasue the air would be colder here? Because there is more air traffic?

I have no idea really, but maybe the air temperature argument holds water because this photo was taken early yesterday, on a clear and frosty morning, and behold the vapour trails like arrows in the sky pointing directly to Heathrow.

Quite pretty really, innit??

guess_which_way_heathrow.png/>