Ozone and stagnant air

2006-06-18 05:14:22.000 – Neil Lareau,  Observer

I always forget just how thick summer fog can be. Visibility is about 25 feet this morning. The thickness is in large part a function of temperature… the warmer the air the more moisture content it can have and the bigger the cloud droplets can become and thus the worse the visibility can get. Temperatures today are very warm (Mid 50s is very warm for us during the night!)

The atmospheric configuration of pressure systems, and thus wind flows, will be perfectly aligned today to not only produce extremely warm temperatures but also to allow unhealthy levels of ozone to dwell in the simmering air. Surface high pressure moving off the mid Atlantic coast, a scenario known as a Bermuda high, will create a southwesterly flow of air that forces hot and moisture laden air into New England. At the same time a ridge of upper level high pressure will have its central axis directly across New England. This upper level ridge will act like a lid trapping and stagnating the air near the surface allowing it to bake in the sun but also disallowing the normal mixing processes that help to distribute and dissipate primary pollutants suspended in the atmosphere. This will allow secondary reactions to occur amongst these primary pollutants and the formation of tropospheric Ozone.

“Tropospheric ozone is a pollutant which affects large geographical areas when weather conditions are favorable for its formation. Ozone at ground-level is a secondary pollutant which forms in the atmosphere as a by-product of chemical reactions that take place between other chemical compounds (i.e. ozone precursors) emitted from automobiles, diesel trucks and industrial sources. Specifically, these ozone precursors are volatile organic compounds (VOCs) and oxides of nitrogen (NOx). These compounds react together when exposed to strong ultraviolet radiation from the sun during hot summer weather.” (AIRMAP)

Today is the perfect day for ozone production… the result is the following:

331 AM EDT SUN JUN 18 2006

…AIR STAGNATION ADVISORY REMAINS IN EFFECT FROM 8 AM THISMORNING TO 8 PM EDT THIS EVENING…

THE NEW HAMPSHIRE DEPARTMENT OF ENVIRONMENTAL SERVICES ISPREDICTING UNHEALTHY AIR QUALITY IN THE SOUTHERN HALF OF THESTATE…AND HIGHER ELEVATIONS OF THE WHITE MOUNTAINS ON TODAY.ACTIVE CHILDREN AND ADULTS AND PEOPLE WITH RESPIRATORY PROBLEMSWHO ARE IN THESE AREAS SHOULD AVOID PROLONGED OUTDOOR ACTIVITY.

I don’t know about you, but I for one would enjoy living in a world where it wasn’t ever dangerous to enjoy prolonged outdoor activities.

To learn more about tropospheric ozone and the observatory’s involvement in measuring it visit AIRMAP

Neil Lareau,  Observer