Although nitrogen oxides form ozone downwind, its immediate effect is to break the ozone into O and O 2 . A schematic illustration is given to the right, 'looking down' over the ozone plume as it passes over a large NOx source. Daily ozone forms and moves with the surface wind. Additionally, the ozone chemisrty cycle takes time to 'max out'. Another result of transport and the time required for the chemistry cycle is that ozone values often peak after the incident solar radiation and temperature have peaked.
Ozone also travels over the ocean and over other large bodies of water.
Because there are no monitors located in these areas, the ozone map will not represent these areas accurately.