Editing Talk:2004: Sun and Earth
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It take much more than a energy gradient to result in convection - both gravity and different density regions in the medium must be present - generally convective system are in media that become less dense at higher temperatures, and are heated in the region of lower gravitational potential. The media expands as it heats becoming less dense then rises against gravity as cooler higher density media flows to replace it. Since the two flows can not occur simultaneously in the same location, generally the flow self organizes into cells or adjacent regions of counter flow. | It take much more than a energy gradient to result in convection - both gravity and different density regions in the medium must be present - generally convective system are in media that become less dense at higher temperatures, and are heated in the region of lower gravitational potential. The media expands as it heats becoming less dense then rises against gravity as cooler higher density media flows to replace it. Since the two flows can not occur simultaneously in the same location, generally the flow self organizes into cells or adjacent regions of counter flow. | ||
Neither the sun which is a main sequence star in its stable Hydrogen burning phase nor the Earth are appreciably heated by gravitational collapse. For the sun gravity does provide the pressures needed for, and contains, the resulting fusion processes that do provide the energy released by the sun. The Earth core is heated by the decay of radioactive elements and the energy released is in very near equilibrium with the energy lost to the surface and ultimately radiated away along with the energy received from external sources (overwhelmingly from the sun). This has resulted in a stable internal temperature profile and surprisingly stable surface temperatures with in a very few degrees (<15C) for billions of years.[[Special:Contributions/162.158.126.76|162.158.126.76]] 17:17, 9 June 2018 (UTC) | Neither the sun which is a main sequence star in its stable Hydrogen burning phase nor the Earth are appreciably heated by gravitational collapse. For the sun gravity does provide the pressures needed for, and contains, the resulting fusion processes that do provide the energy released by the sun. The Earth core is heated by the decay of radioactive elements and the energy released is in very near equilibrium with the energy lost to the surface and ultimately radiated away along with the energy received from external sources (overwhelmingly from the sun). This has resulted in a stable internal temperature profile and surprisingly stable surface temperatures with in a very few degrees (<15C) for billions of years.[[Special:Contributions/162.158.126.76|162.158.126.76]] 17:17, 9 June 2018 (UTC) | ||
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