Hot Air Balloons and Wind Gusts

This video was made of some experiments aimed at determining how a hot air balloon would respond to a wind gust. We know that a hot air balloon tracks the wind speed, but would it track the gusts?

Category:

Science & Technology

Tags:

• DDWFTTW
• DWFTTW
• downwind
• hot
• air
• balloon
• gust

[1XenonXenon1]

It would be hilarious if i passed by a parking lot and saw somebody driving in circles really fast.

[spork33]

@1XenonXenon1

That's why I have the weighted helium balloon and video camera. I can make like I'm doing "science" so people don't think I'm crazy. Same reason I carry a fake cell phone. Otherwise I'm just another nut walking down the street talking to invisible people.

[jjcote]

Helium diffuses through a mylar balloon more slowly than a latex one, and you can therefore keep it at neutral buoyancy longer without adjustment.

[spork33]

@jjcote

An excellent point. Unfortunately, my local scientific supply shop (Chevy's) didn't have the mylar balloons on hand : (

[AtomicRooster190]

I think you'll always have a little air coming through the HVAC system.

For lateral acceleration, I believe your experiment shows buoyancy rather than gust because once the acceleration reaches a steady state (car moving at constant speed), the air will no longer be moving (much). It's only while turning in that the air will be moving to form a wind or gust.

[spork33]

@AtomicRooster190

I'm sure it's not possible to make the car completely airtight, but I set the A/C on recirc and set the fan at 0 when I want no airflow. It seems to work pretty well. I tested it with smoke from a match and found it to be suitable for my purposes.

With the car going in a circle at constant speed the car experiences constant inward acceleration. To the balloon this is essentially equivalent to a constant linear acceleration - and should simulate a steadily building gust.

[sp4jx7]

Any static attraction involved?

Did you get pulled over for the erratic driving?-)

[kamalmichael]

great thinking.great experiment

[aether222]

@spork33 I guess you are right, though your body would be lighter than the water if you were floating on top not drowing so your head was out, but by having part of your body out of the water you have gained neutral buoyancy.

Now if the hot air balloon were rising or if your body was rising then any acceleration of the medium would cause acceleration faster than the medium, and the balloon or swimmer were falling then it would lag behind the medium, and if neutral you would be perfectly in sync

[spork33]

@aether222

Of course if you're floating with neutral buoyancy in a pool you would neither advance or retreat relative to the pool enclosure if it were accelerated. I suspect you'd agree with that. The purpose of this experiment was different in a sense. Most people know that a hot air balloon drifts along at wind speed; but most also believe that it would lag an abrupt change in wind speed before again coming to equilibrium at the new wind speed. This shows there would be no lag.