The Science Behind Denver's Brown Cloud

The bad air in Denver is notorious. It’s so bad that it has a name – the Brown Cloud.


What is a temperature inversion?

Warm air is lighter than cold air. Hot air balloons rise because the warm air inside the balloon is lighter than the cold air surrounding it. In the wintertime, the sun warms the surface of the earth during daylight hours. This warm air rises and mixes with other atmospheric gases. When the sun goes down, the surface area cools and the air gets colder. The less dense warm air high up in the atmosphere often blankets the colder air that rests closer to the surface of the earth. Because the colder air is more dense than the warm air, the colder air is trapped close to the earth and the atmospheric gases do not mix. This is a temperature inversion.

Why is a temperature inversion bad for air quality? 


Temperature Inversion Demonstration

Warm water, like warm air, is less dense than its cold counterpart. You can demonstrate the effects of a temperature inversion by using bottles of warm and cold water. Fill an empty juice bottle with warm colored water and carefully place it over a similar bottle of colored cold water. Do the liquids mix?

Now, place the cold water bottle over the warm water bottle.



For complete step by step instructions and more on temperature inversions, visit the Brown Cloud Temperature Inversion Experiment Page.


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Comment (1)

  • Tatvachintan Reply

    Wow it’s simple yet amazing chemical/physical process but quite amazing yet.

    March 13, 2014 at 1:23 am

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