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Facts about the Atmosphere for Kids

An atmosphere may be retained for a longer duration, if the gravity is high and the atmosphere’s temperature is low. Some planets consist mainly of various gases, but only their outer layer is their atmosphere.

  • The term stellar atmosphere describes the outer region of a star, and typically includes the portion starting from the opaque photosphere outwards.
  • Earth’s atmosphere, which contains oxygen used by most organisms for respiration and carbon dioxide used by plants, algae and cyanobacteria for photosynthesis, also protects living organisms from genetic damage by solar ultraviolet radiation.
  • Its current composition is the product of billions of years of biochemical modification of the paleoatmosphere by living organisms.
  • Atmospheric pressure is the force per unit area that is always applied perpendicularly to a surface by the surrounding gas.
  • It is determined by a planet’s gravitational force in combination with the total mass of a column of gas above a location.
  • Units of air pressure are based on the internationally recognized standard atmosphere (atm), which is defined as 101,325 Pa (or 1,013,250 dynes per cm).
  • The pressure of an atmospheric gas decreases with altitude due to the diminishing mass of gas above each location.
  • However, atmospheres are not uniform in temperature, so the exact determination of the atmospheric pressure at any particular altitude is more complex.
  • Surface gravity, the force that holds down an atmosphere, differs significantly among the planets.
  • For example, the large gravitational force of the giant planet Jupiter is able to retain light gases such as hydrogen and heliumthat escape from lower gravity objects.
  • Second, the distance from the sun determines the energy available to heat atmospheric gas to the point where its molecules’ thermal motion exceed the planet’s escape velocity, the speed at which gas molecules overcome a planet’s gravitational grasp.
  • However, over the past 3 billion years the Earth may have lost gases through the magnetic polar regions due to auroral activity, including a net 2% of its atmospheric oxygen.
  • These planets have hydrogen-helium atmospheres, with trace amounts of more complex compounds.
  • Two satellites of the outer planets possess non-negligible atmospheres: Titan, a moon of Saturn, and Triton, a moon of Neptune, which are mainly nitrogen.
  • Other bodies within the Solar System have extremely thin atmospheres not in equilibrium.
  • However, the exosphere can extend from 500 up to 10,000 km above the surface, where it interacts with the planet’s magnetosphere.
  • Conversely, studying surface of earth leads to an understanding of the atmosphere and climate of a planet — both its present state and its past.