Atmosphere of Mars slowly decreased to very low concentrations, with no layer detectable above 35 km. The reporting scientists think that the observed polar ozone layers are the result of the same atmospheric circulation pattern that creates a distinct oxygen emission identified in the polar night and also present in Earth's atmosphere. This circulation takes the form of a huge Hadley cell in which warmer air rises and travels toward the south pole before cooling and sinking at higher latitudes. Mars is on a quite elliptical orbit and has a large axial tilt, which causes extreme seasonal variations in temperature amongst the northern
Modified atmosphere and its replacement with other gases can reduce or delay oxidation reactions and microbiological spoilage. Oxygen scavengers may also be used to reduce browning due to lipid oxidation by halting the auto-oxidative chemical process. The modification process generally lowers the amount of oxygen (O) in the headspace of the package. Oxygen can be replaced with nitrogen (N), a comparatively inert gas, or carbon dioxide (CO). A stable atmosphere of gases inside the packaging can be achieved using active techniques, such as gas flushing and compensated vacuum, or passively by designing “breathable” films. The first recorded beneficial effects of using modified