Earth's Air Divided By Chemical Equator

This model representation shows the chemical equator found in the study. The colors indicate the carbon monoxide concentrations on 30 January 2006; red is polluted air and blue is clean air.Credit: Glenn Carver, Cambridge University

From Live Science:

Scientists have found a temporary "chemical equator" that separates the heavily polluted air of the Northern Hemisphere from the cleaner air of the Southern Hemisphere over the Western Pacific — only it isn't where they expected to find it.

The Northern Hemisphere tends to have more polluted air than the Southern Hemisphere because it has more cities, more population in those cities on average and more industry. And each hemisphere's air masses tend to stay segregated from one another. That allows scientists to "see" chemical boundaries between the air masses of hemispheres by monitoring big changes in levels of air pollution.

These boundaries, or chemical equators, can typically be found at a "wall" created by global air circulation patterns that separates Northern and Southern hemispheric air. Called the Intertropical Convergence Zone (ITCZ), it is a belt of low pressure that circles the Earth roughly at the equator.

This is a good place to look for chemical equators, or partial ones, between the two hemispheres, but it is not where Geraint Vaughan of the University of Manchester in England and his colleagues found one in the Western Pacific.

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