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The atmosphere of Earth is composed of a layer of gas mixture that surrounds the Earth's planetary surface (both lands and oceans), known collectively as air, with variable quantities of suspended aerosols and particulates (which create weather features such as clouds and hazes), all retained by Earth's gravity.
The spectrum of sunlight has approximately the spectrum of a black-body radiating at 5,772 K (9,930 °F), [12] interspersed with atomic absorption lines from the tenuous layers above the photosphere. The photosphere has a particle density of ~10 23 m −3 (about 0.37% of the particle number per volume of Earth's atmosphere at sea level). The ...
They are dark absorption lines, seen in the optical spectrum of the Sun, and are formed when atoms in the solar atmosphere absorb light being emitted by the solar photosphere. The lines are named after German physicist Joseph von Fraunhofer , who observed them in 1814.
Out of an average 340 watts per square meter (W/m 2) of solar irradiance at the top of the atmosphere, about 200 W/m 2 reaches the surface via windows, mostly the optical and infrared. Also, out of about 340 W/m 2 of reflected shortwave (105 W/m 2 ) plus outgoing longwave radiation (235 W/m 2 ), 80-100 W/m 2 exits to space through the infrared ...
The Sun is composed primarily of the chemical elements hydrogen and helium; they account for 74.9% and 23.8%, respectively, of the mass of the Sun in the photosphere.All heavier elements, colloquially called metals in stellar astronomy, account for less than 2% of the mass, with oxygen (roughly 1% of the Sun's mass), carbon (0.3%), neon (0.2%), and iron (0.2%) being the most abundant.
The mesopause, at an altitude of 80–90 km (50–56 mi), separates the mesosphere from the thermosphere—the second-outermost layer of Earth's atmosphere. On Earth, the mesopause nearly co-incides with the turbopause, below which different chemical species are well-mixed due to turbulent eddies. Above this level the atmosphere becomes non ...
One layer represents the global relief including bedrock over Antarctica and Greenland, and another layer the global relief including ice surface heights. Both layers include bathymetry over the oceans and some of Earth's major lakes. ETOPO1 land topography and ocean bathymetry relies on SRTM30 topography and a multitude of bathymetric surveys ...
These stellar outer layers can be modeled by different computer programs. Often, calculated models are used, together with other programs, to calculate synthetic spectra for stars . For example, in varying the assumed abundance of a chemical element, and comparing the synthetic spectra to observed ones, the abundance of that element in that ...