Take a balloon filled with helium outside on a cold day, and it begins to shrink.
Michelle Coulter worked at Special Occasions Party Supply for about three weeks when a customer first noticed this on her shift.
“He went out and he came back in and said it’s deflating,” Coulter said.
At first Coulter thought the balloon had a leak.
“It took two times before I realized it must be the cold that was doing it,” Coulter said.
The Ideal Gas Law is an equation that can be used to explain the relationship between pressure, temperature, and density.
“The reason that the balloons deflate in the cold weather is because the helium is denser than the air,” Coulter said. “So when it gets cold the molecules will gather together and make the balloon have less volume.
When the temperature is colder, the pressure will also decrease, but the density will increase.
“We have to explain that to people because when they come in and they get their balloons when it’s warm in here, but when they walk outside they start to look like they’re deflating and they panic,” Coulter said.
The balloon isn’t actually deflating. The gas inside is just taking up less space.
“We just tell them, don’t panic. As soon as you get back in where it’s warm they’ll pop back up. Don’t leave them in a car overnight. Don’t leave them in a car overnight. Don’t leave them outside or anything like that,” Coulter said.