Phospherous in glowsticks. Follow package directions.Sticks must be shaken vigorously or encapsulted phophorous must have capsule ruptured, depending on manufacturer. Use times vary. Usually 2 to 4 hours, Consult package.
As the flame burns it heats the air around it making the air less dense than the cooler air above, the warm air particles rise to the top of the balloon and the balloon rises with the air. Essentially a hot air balloon uses a convection current to stay in the air.
kites stay in the air they follow the air around the same things with bollons if they are let go they would fly away > moving air (wind ) is required, the angle of the kite gives vertical force to the kite, opposing gravity.