High temperature, high pressure, high ozone and clear skies? Yes!

Every now and then, something comes along in life that can’t be explained – easily; that keeps us guessing and/or has us asking questions.

It just so happens that on Sunday, Jun. 14th, local skies were surprisingly, uncharacteristically clear, for this area for this time of year, anyway – not what one would expect. Keep in mind there was no wind, no rain in the forecast and temperatures that day got close to the century mark if not above that.

DSCN0406 (340x255)That combination – no wind or rain and high temperature – is typically a recipe for smog – yes, the unsightly, unpleasant and unhealthy air nemesis that s-m-o-g is. According to the San Joaquin Valley Air Pollution Control District via its RAAN (Real-time Air Advisory Network) provision (accessible here), ozone, for at least part of the day, was in the unhealthy-for-sensitive-groups range. So, what could have accounted for skies being as clear as they were?

Jun. 14, 2015 being a Sunday, the probability is high that the area’s motor vehicle activity is reduced compared to what typically is the case on weekdays and perhaps because of this the triggers necessary for visible smog to form in the atmosphere just didn’t exist. The triggers being referred to here are smog-forming chemicals and substances and conditions like volatile organic compounds and particulates in the presence of sunlight. Yes, the sun was shining that day and abundantly. So, maybe, just maybe, due to decreased motor vehicle activity the right conditions or combination of elements just wasn’t there for smog to appear and hence skies were clear.

Yet, at the same time according to RAAN data for Central Fresno for Jun. 14th at 11:00 a.m. the ozone reading was 59 parts per billion (ppb) of air – this is borderline good/moderate. Meantime, at the noon hour, the ozone concentration reached 65 ppb, by 5 p.m. ozone levels were 77 ppb, topping out at 78 ppb just two hours later. High ozone readings, these are.

The 77 and 78 ppb readings correspond with air quality that is unhealthy for sensitive groups. See detailed data here.

For the time being, this is going to be one of those unsolved mysteries. Despite this deficit, the clear-air condition had to be a welcome one. A rare event if ever there were one. Indeed.

For more on unexplained phenomena, see “Air in America: A world of contrasts and contradictions.” That post’s last sentence is quite fitting here and definitely bears repeating.

“Any way you look at it, air in America, it’s nothing if it isn’t colorful and interesting and imperceptible if not puzzling all at the same time.”

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