It's hard to explain but also quite general - a couple of good entries already. I have these as well from a few years back. This one:
https://www.facebook.com/photo.php?f...9&l=ea89b580b1
then this one to explain it:
https://www.facebook.com/photo.php?f...9&l=f205025c71
for some reason Flickr wouldn't let me upload them