Atmospheric chemistry - Ozone clouds over the Atlantic

Ozone in the atmosphere has many useful functions. Most of it is in the stratosphere (above 10 to 20 km) and only ten per cent is in the troposphere (the region down to ground level), where it helps to remove undesirable emissions. The two regions are usually separated, dynamically, by the tropopause, but new measurements taken on airliners show that pockets of extremely high ozone concentration are somehow getting from the stratosphere into the troposphere over the tropical Atlantic.