Hot Air Balloons What does keep hot air balloons flying? It's a basic principle: hot air goes up and cold air goes down. A hot air balloon has three major parts: the basket, the burner and the envelope. The basket is made of wicker and it's where passengers are. The envelope is color fabric balloon. The burner is above passengers' heads and it gives a huge flame to heat the air in the envelope. The pilot can control the altidute by heating and cooling the air in the envelope. Before launching the balloon, the pilot knows the direction of the wind. So he or she knows where the balloon will go. What if you want to change the direction of the balloon? The air has different layers in which the direction of the wind may be different. If the pilot wants to change the direction of the balloon, he or she just needs to change the altitude. Keep in mind that some days the direction of the wind between layers is negligible. Other days the difference is quite strong. ------ I hope I haven't made a lot of silly mistakes in this text. I don't feel very well and I'm quite sleepy right now.