People releasing a Khom Loy (Hot Air Lantern) at the YeePeng Festival in Sansai Thailand 56
In Chiang Mai, this was considered part of the Loy Krathong Festival.
It begins with a lengthly Buddhist ceremony, followed by a candle-lit procession, and then a massive release of Khom Loys (hot air lanterns) by the participants at the event.
Many of the participants remain and continue to release more lanterns.
The YeePeng Festival hasn't been held the last couple years due to safety concerns.