Thursday, January 19, 2017

Temperature Inversion

What is Temperature Inversion?

Basic Scientific Fact: cold air is denser than warm air and in a normal weather pattern this helps circulate air and dilute pollutants. Air normally gets cooler the higher in altitude it goes—to be more specific—3.5ยบ cooler every 1,000 feet in altitude. A temperature inversion is exactly what it sounds like, the cold and warm air switch position. In our area, there are 3 possibilities for the cause of an inversion layer:

1. A low-pressure system, warmer air, is pushed down towards the earth’s surface, while a high-pressure system, cooler air, moves over and traps the warmer air; this is most common after a storm.

2. The air near the ground rapidly loses its heat on a clear night. In this situation, the ground becomes cooled quickly while the air above it retains the heat the ground was holding during the day.

3. Topography can also play a role in creating a temperature inversion. Cold air can flow from mountain peaks down into valleys. This cold air then pushes under the warmer air rising from the valley, creating the inversion. Inversions can also form in areas with significant snow cover because the snow at ground level is cold and its white color reflects almost all heat coming in. This means the air above the snow is often warmer because it holds the reflected energy. 

In and around the Tahoe Basin, this can happen usually after storms and is evident in local valleys on a small and large scale. You can see examples of this when you drive on Highway 267 from Truckee to Northstar in the early morning. There is usually fog low to the ground in the surrounding Martis Valley. On a larger scale, Reno, Nevada in the Truckee Meadows is constantly experiencing inversion layers over the city. This occurs in the weeks after a winter storm or when cold air from the Sierra crest settles in and pushes the warm air up, causing the inversion. This can mean clouds and no direct sunlight from days to weeks!

How Does it Affect Us?

Directly: the buildup of moisture due to the inversion layer can cause early morning fog on your way to work or that pesky frost you must scrape off your windshield of the car before even beginning your commute.

Indirectly: An atmospheric stabilization can lead to a concentrate of pollutants like car exhaust and wood fireplace smoke. Long periods of an inversion layer can cause thick smog to form in the Lake Tahoe Basin and Truckee Meadows. Trapped smog can cause winter allergies and make existing asthma symptoms worse. Studies have shown that increases in particle pollution in the air, like those from fossil fuels, lead to more hospitalizations for children who have asthma.

What’s a Kid (AdultsToo…) To Do?

Go skiing, sledding, hiking, snowshoeing or any other outdoor activity at higher elevations. Get above the clouds to breath in the fresh air. Your lungs will love you for it.

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