Depending on how early you wake up in the morning and how long you've been in Boise, you may have caught a glimpse of the parade of hot air balloons floating over the city. As part of the annual Spirit of Boise Balloon Classic, these airborne attractions are part of a community effort to bring people together and provide them with a source of family-friendly entertainment. Even if you didn't formally attend the week-long event, you probably enjoyed the spectacle of these colorful, whimsical vehicles floating over the city. You also probably wondered how hot air balloons work.
The science behind hot air balloons is deceptively simple. Hot air rises. Therefore, filling the balloon or envelope with heated air allows it to float. In reality, the process of launching a hot air balloon is much more complex and it takes an experienced pilot to launch one successfully.
This process begins by unwrapping the envelope and attaching it to the burner and basket. Then, large fans are used to inflate the balloon with cold air. Next, the pilot uses the attached burner to heat the air inside the envelope. Heating the air in the envelope manipulates the balloon's internal pressure and density. The increased pressure keeps the balloon inflated while the reduced density enables it to float. To keep the balloon afloat, it's imperative that pilots maintain the correct balance of air pressure and density within the balloon.
Once the balloon is up in the air, pilots utilize various weather tools to navigate the varying wind directions at different altitudes. Pilots can't actually steer hot air balloons, so they use a vent at the top of the envelope to adjust the balloon's flying altitude. This adjustment influences the balloon's trajectory. Pilots also use vents on the sides of the balloon to rotate it 360 degrees.
When it's time to land, pilots generally choose a safe, open space. By gradually releasing air from the balloon, the balloon sinks lower and lower until it reaches the landing spot. In some cases, pilots may also use sandbags to aid in the process of landing. When the basket finally touches down, and all the passengers exit it, the balloon is deflated.
