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Astronomy Chapter 10 Notes.pdf

4 Pages
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Department
Astronomy
Course Code
Astronomy 1021
Professor
Trevor Kirsh

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Chapter 10: Planetary magnetosphere, and cause a Atmospheres greenhouse effect that can make a planet’s surface warmer than it would ‘Big picture: view of how terrestrial be otherwise worlds started out and how it • Atmospheric pressure is from the ended up different collisions of individual atoms or molecules in an atmosphere • Atmospheres affect planets in many • The higher you go the less gas is ways above you so the less pressure/weight • They absorb and scatter light, you will feel distribute heat, and create the weather • This pressure is measured in barometer aka bar that can lead to erosion • The greenhouse effect allows atmospheres to make a planet warmer How does the greenhouse effect warm than it would be otherwise a planet? • Atmospheric properties differ widely • Greenhouse gases such as carbon among the terrestrial worlds, but we dioxide, methane and water vapor can trace these differences to root absorb infrared light emitted from a planet’s surface causes • The histories of Venus and Mars • So Sun gives off light absorbed by the suggest that major climate change is ground and returned as infrared light the rule, not the exception. Mars was that gets trapped by the greenhouse once warm and wet, but its small size effect and fact of a magnetic field caused it • The absorbed photons are quickly to lose gas and freeze over 3 billion or reemitted, but in random directions more years ago. • The result acts much like a blanket, • Venus may once have had oceans, but warming the planet’s surface, aka its proximity to the Sun doomed it to a global average temperature runaway greenhouse effect • Earth is the only exception, its a planet Why do atmospheric properties vary where the climate remained relatively with altitude? Atmospheric structure is determined by stable. However there is no guarantee • that Earth will remain as hospitable in the way atmospheric gases interact the future, especially as we tinker with with sunlight balance of greenhouse gases that has • On Earth, the basic structure consists kept our climate stable of the troposphere, where most greenhouse warming occurs, the stratosphere, where ozone absorbs ultraviolet light from the Sun, the 10.1 thermosphere where solar X-rays are What is an atmosphere absorbed, and the exosphere the • An atmosphere is a layer of gas that extremely low density outer layer of the surrounds a world, it can create atmosphere pressure, absorb and scatter sunlight, • Only Earth has a stratosphere create wind and weather, interact with the solar wind to create a • A magnetosphere is a protective • More greenhouse effects means bubble surrounding our planet warmer planet deflecting solar wind particles • The particles that do get into the How does a planet gain or lose magnetosphere moves along the atmospheric gases? magnetic field lines, making up a • Three sources of atmospheric gases charged particle belt are outgassing, evaporation, or • Its really pretty and we call it the aurora sublimation • Outgassing is when planets have water 10.2 and gas trapped in the interiors that causes volcanic eruptions What creates wind and weather? • Some worlds with little atmosphere, • Global wind patterns are shaped by also has surface ejection by tiny atmospheric heating and the Coriolis impacts of particles and photons of effect caused by a planet’s rotation high energy knocking other atoms out • Warm air moves upwards and cool air of the surface falls so the air near the equator are • Four loss processes are condensation, warmer and so they flows towards the chemical reactions with surface poles and so it creates this wind materials, the stripping of gas by the pattern solar wind, and thermal escape • Coriolis effect is when the Earth’s • Condensation is when gases condense equatorial regions travels faster than and fall as snow or rain polar regions so the air moves away • Chemical reaction is when gas is from the equator and so it becomes incorporated into metal or rock and circulating wind in the Northern or rusting is an example, when oxygen Southern hemisphere absorbed into iron • Convection in the troposphere can lead • Sola
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