What happens to the pressure change inside a rising balloon?

[axer]

Hello, so i have a question regarding the pressure change inside a rising hydrogen balloon,

I know that the pressure change of air outside is decreasing(as we go up = less pressure)

And as the balloon is rising it's increasing its volume.

but what happens do the pressure change inside the balloon as it rises? decreses or increases?

 

[russ_watters]

Hello, so i have a question regarding the pressure change inside a rising hydrogen balloon,

I know that the pressure change of air outside is decreasing(as we go up = less pressure)

And as the balloon is rising it's increasing its volume.

but what happens do the pressure change inside the balloon as it rises? decreses or increases?

Constant mass, increasing volume means what?

 

[axer]

Constant mass, increasing volume means what?

according to Boyle's law increasing volume means deceasing pressure,..

But can it be possible to have a decrease in the change in pressure both inside and outside?

 

[russ_watters]

according to Boyle's law increasing volume means deceasing pressure,..

But can it be possible to have a decrease in the change in pressure both inside and outside?

Why not? What actually causes the change of pressure/volume inside if the envelope is loose?

 

[axer]

What actually causes the change of pressure/volume inside if the envelope is loose?

I didn't quite understand what you meant. P = 1/V is based on a constant T..

 

[russ_watters]

I didn't quite understand what you meant. P = 1/V is based on a constant T..

I don't mean equations, I mean objects/concepts. You have a balloon. It expands. Why?

If this were a party balloon at home on your birthday, you would answer "the balloon expands because I am blowing air into it." Does that happen here? If not, what physically is happening?

 

[axer]

I don't mean equations, I mean objects/concepts. You have a balloon. It expands. Why?

If this were a party balloon at home on your birthday, you would answer "the balloon expands because I am blowing air into it." Does that happen here? If not, what physically is happening?

my explanation is that because the difference in pressure above is low therefore the volume of the balloon is increasing.

Other explanation is that because the volume of the air above is increasing, therefore the volume of the balloon is.. V(object)=V(air)

I don't know.. please tell me in your understandings

 

[russ_watters]

my explanation is that because the difference in pressure above is low therefore the volume of the balloon is increasing.

Other explanation is that because the volume of the air above is increasing, therefore the volume of the balloon is.. V(object)=V(air)

I don't know.. please tell me in your understandings

There might be a language issue here, so fist a minor edit/correction of your wording:
..."the difference in pressure above is low therefore the volume of the balloon is increasing."

That has extra words in it. You should simply say that:
"as the balloon rises, the pressure of the air around it decreases."

Is that what you meant?

 

[axer]

There might be a language issue here, so fist a minor edit/correction of your wording:
..."the difference in pressure above is low therefore the volume of the balloon is increasing."

That has extra words in it. You should simply say that:
"as the balloon rises, the pressure of the air around it decreases."

Is that what you meant?

Yes, i meant this.

 

[russ_watters]

Yes, i meant this.

...and if the pressure of the air around the balloon is decreasing, then the balloon will have a higher pressure than the air around it...unless it too expands.

 

[axer]

...and if the pressure of the air around the balloon is decreasing, then the balloon will have a higher pressure than the air around it...unless it too expands.

ooh, ok i think I got it, since the balloon is increasing in volume, therefore the pressure is decreasing. Ok thanks!

 

[sophiecentaur]

ooh, ok i think I got it, since the balloon is increasing in volume, therefore the pressure is decreasing. Ok thanks!

You have to remember that any 'serious' balloon (like a meteorological ballon) has a vast envelope that's only partially filled at sea level. By the time it is at a design height of several tens of km, the Helium inside has expanded and the envelope is more or less spherical. It's not a good idea to use a balloon with an elastic membrane that's under tension at low level because it will stop rising if the gas inside is constrained by the envelope - no lifting power.