“What is that?”: Stratospheric balloons over Rapid City

Two white dots in the sky have been befuddling residents and visitors alike with their slow movement and peculiar shape
Raven Stratospheric Balloon: credit NWS Rapid City

Raven Aerostar Stratospheric Balloon: credit NWS Rapid City

RAPID CITY, S.D. – Two white dots in the sky have been hovering over Rapid City since Saturday, mesmerizing onlookers with their almost stationary position and peculiar glint off the sun.

Raven Stratospheric Balloon: credit NWS Rapid City

Raven Stratospheric Balloon: credit NWS Rapid City

These are stratospheric balloons from a company called Raven Aerostar, based in Sioux Falls. Aerostar says the flights serve a variety of missions – from “achieving customer objectives to Research and Development to continually improve technology.” They have a distinct “jellyfish” look to them that helps keep them afloat in the very thin air.

Earth's atmosphere - Credit NOAA

We live in the troposphere, where the vast majority of our weather takes place, along with most of the planet’s oxygen, nitrogen and other important gasses. The stratosphere sits on top of the troposphere and has vastly different properties like thinner air and rising temperatures as you ascend through it.

These balloons are able to hover almost at a standstill because there is very little to no wind at that height of the atmosphere. The stratosphere actually fluctuates in height based upon the seasons and your proximity to the equator. The bottom of the stratosphere can be as high as 65,000 feet at the equator and as low as 23,000 feet at the poles in winter.

You wouldn’t want to go there though, it’s full of ozone – which is good for absorbing UV radiation, but bad for breathing.

The Black Hills are no stranger to these stratospheric balloons, being home to the Stratobowl and the birthplace of the space age in 1934 and 1935 when the Army Air Corps and National Geographic sent a balloon 72,395 feet.

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