Ozone layer an altitude of 100 kilometers from the planet's surface. The photochemical mechanisms that give rise to the ozone layer were discovered by the British physicist Sydney Chapman in 1930. Ozone in the Earth's stratosphere is created by ultraviolet light striking ordinary oxygen molecules containing two oxygen atoms (O), splitting them into individual oxygen atoms (atomic oxygen); the atomic oxygen then combines with unbroken O to create ozone, O. The ozone molecule is unstable (although, in the stratosphere, long-lived) and when ultraviolet light hits ozone it splits into a molecule of O and an individual atom of oxygen, a continuing process
Mixed layer of salty water subducted in the subtropics (found in all subtropical ocean gyres). Barrier layer formation in the subtropics is associated with seasonal change in the mixed layer depth, a sharper gradient in sea surface salinity (SSS) than normal, and subduction across this SSS front. In particular, the barrier layer is formed in winter season in the equatorward flank of subtropical salinity maxima. During early winter, the atmosphere cools the surface and strong wind and negative buoyancy forcing mixes temperature to a deep layer. At this same time, fresh surface salinity is advected from the rainy regions in the tropics.