(YouTube Link)
The Chiang Mai Yi Peng Festival is an Buddhist holy day in Thailand. That evening, celebrants send send burning lanterns aloft, floating on hot air. According to YouTube user bugzila:
[...]it is the great festival of Lanna duly succeeded from ancient age. "Yi Peng" or full-moon day of second lunar month of Lanna villagers is corresponding to the full-moon day of 12th month of central region during the end of raining season and beginning of cold season when the climate is very nice and fair. One tradition of Lanna other than Loi Kra Thong on the river is to light up the lantern and float up in the sky based on their belief that to pay worship to Phra Ket Kaew Julamanee in the heaven or to relief one' bad luck for more auspicious life.
Via Urlesque
Chiang Mai is a place where both backpackers and luxury tourists can enjoy themselves to the fullest.
I made one of these as a kid. We used dry-cleaning bags and candles, pre-heating the air in the bag with a tray of bbq coals.
Still... The successful mass release of these in low winds is indeed beautiful.
I think they are originally Chinese...but in the Chinese version you write your wishes on the lanterns before setting them off. They have a big festival every new year in Pingxi, Taiwan
http://www.youtube.com/watch?v=oEAIdbBwQGM