Part 1 of Essay
The stratospheric ozone layer exists at altitudes between about 10 and 40km depending on latitude, just above the tropopause. Its existence is crucial for life on earth as we know it, because the ozone layer controls the absorption of a portion of the deadly ultraviolet (UV) rays from the sun. UV-A rays, including waveleng ....

Part 2 of Essay
.... several decades as a tracer for stratospheric circulation. Initial measurements were made by ozonesondes attached to high altitude balloons, by chemical-sondes or optical devices, which measured ozone concentrations through the depletion of UV light. However, the need to measure ozone concentrations from the surface at regular intervals, led to the development of the Dobson spectrophotometer in the 1960s. The British Antarctic Survey has the responsibility to routinely monitor stratospheric ozone levels over the ....