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Colorado Weather: Cold air causes brown cloud to return

Inversion of cold air traps air pollution
Inversion of cold air traps air pollution 01:15

Our recent blast of snow and cold air in Colorado not only caused driving problems with the slick roads but it also did a number on our air quality along the Front Range Urban Corridor. It caused cold air and air pollution mostly from vehicle traffic, smoke stacks and wood burning to be trapped in the lower elevations.

Denver viewed from Lookout Mountain camera. Credit: CBS4

Denver and the Front Range Urban Corridor including Fort Collins and Greeley have an Action Alert Day in place for Wednesday with moderate air quality and poor visibility. For the Colorado Department of Public Health and Environment Action Day we are urged to reduce driving and residential burning restrictions are in place.

Credit: CBS4

Cold air tends to be heavier and denser that warm air. This causes the air to pool into lower elevations such as river valleys. Denver actually lies in the valley of the Platte River.

Credit: CBS4

In fact, years ago the stretch of I-25 that runs thru Denver was sometime referred to as the "Valley Highway".

Downtown Denver viewed from the Tech Center area. Credit: CBS4

At the same time the temperature profile that is set up includes colder air below warmer air. Known as an inversion, this set up traps any air at the surface not allowing the pollutants to mix out. 

As temperatures warm and wind strengthens over the next few days the air over our region should begin to clear.

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