where do auroras occur in the atmosphere

Most auroras occur in the E-layer of the ionosphere, which is located 90 km to 150 km (60 mi to 90 mi) above the earth’s surface. As they do so, the "mirror effect" transforms their directions of motion, from perpendicular to the field line to a cone around it, which gradually narrows down, becoming increasingly parallel at large distances where the field is much weaker. The appearances of arcs, rays, curtains, and coronas are determined by the shapes of the luminous parts of the atmosphere and a viewer's position. Other types of auroras have been observed from space, e.g. As already mentioned, it happens most readily when the interplanetary field is directed southward, in a similar direction to the geomagnetic field in the inner regions of both the north magnetic pole and south magnetic pole. Because the highest parts of the atmosphere contain a higher percentage of oxygen and lower particle densities, such collisions are rare enough to allow time for oxygen to emit red light. In turn, this affects the average probability of opening a door through which energy from the solar wind can reach the Earth's inner magnetosphere and thereby enhance auroras. This page was last updated 6/19/01, University of Alaska's Geophysical Institute. Ano ang Imahinasyong guhit na naghahati sa daigdig sa magkaibang araw? The altitudes where auroral emissions occur were revealed by Carl Størmer and his colleagues, who used cameras to triangulate more than 12,000 auroras. Weird & Wacky, Copyright © 2020 HowStuffWorks, a division of InfoSpace Holdings, LLC, a System1 Company. By signing up for this email, you are agreeing to news, offers, and information from Encyclopaedia Britannica. the io. These particles, mainly electrons and protons, precipitate into the upper atmosphere (thermosphere/exosphere). [56] The electrons and ions that cause the diffuse aurora appear not to be accelerated during precipitation. Ano ang mga kasabihan sa sa aking kababata? Proton auroras are usually observed at lower latitudes. Excitation energy is lost within the atmosphere by the emission of a photon, or by collision with another atom or molecule: Oxygen is unusual in terms of its return to ground state: it can take 0.7 seconds to emit the 557.7 nm green light and up to two minutes for the red 630.0 nm emission. The chronicler has heard about this phenomenon from compatriots returning from Greenland, and he gives three possible explanations: that the ocean was surrounded by vast fires; that the sun flares could reach around the world to its night side; or that glaciers could store energy so that they eventually became fluorescent. But when planning your trip remember: places above the arctic circle have round-the-clock sunlight during about April to September! In Japanese folklore, pheasants were considered messengers from heaven. [26] The phenomenon of pulsating auroras is an example of intensity variations over short timescales, typically with periods of 2–20 seconds. - Answered by a verified Tutor. The electrons responsible for the brightest forms of the aurora are well accounted for by their acceleration in the dynamic electric fields of plasma turbulence encountered during precipitation from the magnetosphere into the auroral atmosphere. What is the hink-pink for blue green moray? In another interpretation, the currents are the direct result of electron acceleration into the atmosphere by wave/particle interactions. Aurora, luminous phenomenon of Earth’s upper atmosphere that occurs primarily in high latitudes of both hemispheres; auroras in the Northern Hemisphere are called aurora borealis, aurora polaris, or northern lights, and in the Southern Hemisphere aurora australis, or southern lights. The width of the magnetosphere abreast of Earth, is typically 190,000 km (30 Re), and on the night side a long "magnetotail" of stretched field lines extends to great distances (> 200 Re). This insight was made possible not only due to scientific magnetometer measurements of the era, but also as a result of a significant portion of the 125,000 miles (201,000 km) of telegraph lines then in service being significantly disrupted for many hours throughout the storm. For example, the Gunditjmara people of western Victoria called auroras puae buae ('ashes'), while the Gunai people of eastern Victoria perceived auroras as bushfires in the spirit world. [14][15] What region of the atmosphere where auroras occur? The charged particles discharge when particles from the Sun hit the inversion layer, creating the noise. Boston: "Mine is disconnected, and we are working with the auroral current. The Dieri people of South Australia say that an auroral display is kootchee, an evil spirit creating a large fire. 1. Auroras seen within the auroral oval may be directly overhead, but from farther away, they illuminate the poleward horizon as a greenish glow, or sometimes a faint red, as if the Sun were rising from an unusual direction. For full treatment, see ionosphere and magnetosphere. What is the hink-pink for blue green moray? In between, some of the current connects directly through the ionospheric E layer (125 km); the rest ("region 2") detours, leaving again through field lines closer to the equator and closing through the "partial ring current" carried by magnetically trapped plasma. The aurora can be seen best at this time, which is called magnetic midnight. [71] Seneca wrote about auroras in the first book of his Naturales Quaestiones, classifying them, for instance as pithaei ('barrel-like'); chasmata ('chasm'); pogoniae ('bearded'); cyparissae ('like cypress trees'), and describing their manifold colors. Because these charged Over the night, they begin with glows and progress towards coronas, although they may not reach them. Auroral events of historical significance, Historical theories, superstition and mythology, The name "auroras" is now the more common plural of "aurora", Boström, Rolf "Observations of weak double layers on auroral field lines" (1992) IEEE Transactions on Plasma Science (, Ergun, R. E., et al. Both incoming electrons and protons may be involved. Venus has no magnetic field and so Venusian auroras appear as bright and diffuse patches of varying shape and intensity, sometimes distributed over the full disc of the planet. [32] Ionospheric absorption makes AKR only observable from space. [43] These electrons often, but not always, exhibit a peak in their energy distribution, and are preferentially aligned along the local direction of the magnetic field.

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