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Name: Gina
Status: Student
Age: 16
Location: N/A
Country: N/A
Date: N/A 

Why is a weather balloon never filled completely with He when it is released?

Q. What would the weather balloon do when it is released?
A. It would rise.
Q. How does the air pressure at high elevations compare with air pressure at low elevations?
A. Air pressure is lower at high elevations than at low elevations.
Q. What happens to the gas inside a balloon when the air pressure outside the balloon drops?
A. The gas inside the balloon will expand until its pressure is the same as the pressure of the air on the outside.
Q. What if the balloon is already full?
A. If the balloon is closed, it will break; if it is open at the bottom, some of the gas inside will escape, which is a waste.

Richard E. Barrans Jr., Ph.D.
Assistant Director
PG Research Foundation, Darien, Illinois

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