Temperature on neptune
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Temperature on Neptune: An Overview
Upper Atmosphere Temperature on Neptune
The temperature in Neptune's upper atmosphere varies significantly depending on the altitude and specific atmospheric conditions. Observations from the occultation of the sun by Neptune suggest that the temperature in the upper levels of the atmosphere, primarily composed of atomic and molecular hydrogen, is approximately 750 ± 150 kelvins1. This high temperature is indicative of the complex interactions and energy dynamics occurring at these altitudes.
Mid-Atmosphere Temperature Variations
In the mid-atmosphere, temperatures are notably lower. Analysis of the 1968 occultation of BD -17° 4388 by Neptune indicates that temperatures near the 5 × 10^14 cm^-3 level are around 140 K2. This region of the atmosphere is nonisothermal, meaning that temperature varies with altitude and location. Diurnal temperature variations are minimal, less than 10 K, suggesting a relatively stable thermal environment in this part of the atmosphere2.
Stratospheric Temperature and Seasonal Changes
Neptune's stratosphere exhibits a quasi-isothermal structure with temperatures ranging from 158 to 164 K above the 0.1-mbar level, as observed from ground-based infrared measurements between 2003 and 20076. These observations show remarkable consistency with earlier spacecraft data, indicating minimal seasonal variability in stratospheric temperatures, with changes less than ±5 K at 1 mbar and ±3 K at 0.1 mbar6. However, significant temperature increases have been noted at high southern latitudes, with a polar enhancement of 7-8 K above the tropopause and a 5-6 K increase throughout the 70-90°S region between 0.1 and 200 mbar6.
Exospheric Temperature Predictions
The exospheric temperature of Neptune, which is the outermost layer of the atmosphere, is predicted to be around 200 K. This is significantly lower than the exospheric temperatures of Uranus, which can reach nearly 800 K, due to differences in magnetic field properties and auroral energy inputs4. The lower exospheric temperature on Neptune suggests a different mechanism of energy distribution compared to other gas giants like Jupiter, Saturn, and Uranus4.
Internal Heat Source and Effective Temperature
Neptune's effective temperature, derived from infrared measurements, is approximately 58.4 K. This low temperature implies the presence of an internal heat source that is about 1.6 times the solar-absorbed power, indicating that Neptune generates significant heat from its interior3. This internal heat contributes to the overall thermal profile of the planet and affects atmospheric dynamics.
Conclusion
Neptune's atmospheric temperatures vary widely across different layers, from the upper atmosphere's 750 K to the stratosphere's quasi-isothermal 158-164 K, and down to the exosphere's predicted 200 K. These variations are influenced by factors such as internal heat sources, magnetic field properties, and seasonal changes. Understanding these temperature profiles helps in comprehending the complex atmospheric processes and energy dynamics on Neptune.
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Ultraviolet Spectrometer Observations of Neptune and Triton
Neptune's upper atmosphere is mostly hydrogen, with methane, acetylene, and ethane at lower levels, and Triton's atmosphere mainly consists of molecular nitrogen with traces of methane near the surface.
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