They are helping many Southeast Michigan communities keep air cleaner. When the Coalition's meteorologists address solar insolation and ultraviolet radiation, they rely on conditions that include the number of days before and after the summer equinox, amount of cloud cover and type of cloud cover. Cloud Cover Cloudless skies are responsible for creating prime conditions for high amounts of solar insolation. Still, because the photochemical process can start at lesser amounts, a completely cloudless sky is not necessary. They must also consider time of day for various types of cloud cover.
Time is important because peak ozone production occurs during peak UV insolation.
That means days with full midday sunshine have the potential to produce more ozone than days with cloud cover at noon. Temperature High temperatures not only increase ozone levels because they are favorable to the chemical reaction, they also increase the amount of hydrocarbon emissions in the air. High temperatures also result in more evaporation of hydrocarbons and, thus, make a double contribution to the formation of ground-level ozone. They tend to transport ozone and ozone precursors from industrial areas upwind of Detroit to the area. They often act, during a lake breeze, to push ozone precursors into the stable layers of the nearby Great Lakes where the chemical reactions that form ozone are accelerated before the pollutant moves and is pushed on-shore.