To me, she seem to be Tsukishiro Hikari from "Wind ~ a breath of heart ~". In the second music video of the game she had the same face, the same dress, the same broad-brimmed hat... and she had the clouds under her...
It was posted on a Haruhi image thread so I assumed it was one.http://www.koichan.net/a/res/24903.html Anyway care to give a link to the pic for comparison?