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Atmospheric pressure is the total weight of the air above unit area at the point where the pressure is measured. Thus air pressure varies with location and weather . If the entire mass of the atmosphere had a uniform density equal to sea-level density (about 1.2 kg/m 3 ) from sea level upwards, it would terminate abruptly at an altitude of 8.50 ...
Mercury, being the closest to the Sun, with a weak magnetic field and the smallest mass of the recognized terrestrial planets, has a very tenuous and highly variable atmosphere (surface-bound exosphere) containing hydrogen, helium, oxygen, sodium, calcium, potassium and water vapor, with a combined pressure level of about 10 −14 bar (1 nPa). [2]
Due to the similarity in pressure and temperature and the fact that breathable air (21% oxygen, 78% nitrogen) is a lifting gas on Venus in the same way that helium is a lifting gas on Earth, the upper atmosphere has been proposed as a location for both exploration and colonization. [9]
The atmosphere of Mars has been losing mass to space since the planet's core slowed down, and the leakage of gases still continues today. [ 4 ] [ 8 ] [ 9 ] The atmosphere of Mars is colder than Earth’s owing to the larger distance from the Sun, receiving less solar energy and has a lower effective temperature , which is about 210 K (−63 °C ...
On Earth, the atmosphere warms the planet, contains the oxygen people breathe, protects against solar radiation and creates the pressure needed for liquid water to remain on the planet's surface.
[8] [9] Since the start of the Cambrian period, atmospheric oxygen concentrations have fluctuated between 15% and 35% of atmospheric volume. [10] 430-million-year-old fossilized charcoal produced by wildfires show that the atmospheric oxygen levels in the Silurian must have been equivalent to, or possibly above, present day levels. [11]
The units of air pressure are based upon the standard atmosphere (atm), which is 101,325 Pa (equivalent to 760 Torr or 14.696 psi). The height at which the atmospheric pressure declines by a factor of e (an irrational number equal to 2.71828) is called the scale height ( H ).
The discovery that GJ 1132b has an atmosphere is a key step in the search for life outside our solar system. Scientists confirm 'Earth-like' planet with atmosphere discovered 39 light-years from Earth