Back by popular demand, more time-lapse Philly movies with Air Quality relevant measurements. This video was made for a presentation at the Franklin Institute to STEM Scholars, a group of STEM minded high students in the city of Philadelphia. It’s always a good thing when the students ask if there are anymore videos to watch!
The NO2 and O3 data are provided by the Philadelphia Air Management Services.
A quick overview of what is going on with the video:
12AM to 6AM – not a lot happening
6AM to 7 AM – Emissions of NO from cars, reacts with O3 making NO2 and reducing O3 concentrations
7AM – noon – Sun rises and photolyzes NO2 (NO2 breaks down to NO + O in sunlight), increasing O3 levels, along with photochemical production of Ozone.
noon – 6 PM – Afternoon gets cloudy – dips are seen in the solar radiation measurement with cloudy conditions
6PM – midnight – At sunset NO2 is no longer photolyzed and increases in concentration. Continued emissions of NO from cars decrease O3 concentration until emissions slow down and the evening settles down into a quasi steady state from about 10 PM onwards.