Thursday, February 28, 2013

Chapter 7 notes con't


Outgassing
            Volcanism also a release gas from earth’s interior onto the atmosphere.
Convection of the mantle creates stresses in the crust called tectonic forces.
Compression forces make mountain ranges.
A valley can form where the crust is pulled apart.
Erosion is a blanket term for weather driven processes that break down or transport rock.
Processes that cause erosion include
            Glaciers
            Rivers
            Wind
Erosion can create new features by depositing debris.


Effects of atmosphere on earth
            Erosion
            Radiation protection:
                        All x-ray light is absorbed very high in the atmosphere.
                        Ultraviolet light is absorbed by ozone.
                        Earth’s atmosphere absorbs light at most wavelengths.
            Greenhouse effect
                        Any gas that absorbs infrared
                        Greenhouse gas- molecules with two different types of elements
                        Not a greenhouse gas- molecules with one or two atoms of the same element.
                        Because of the greenhouse effect, earth is much warmer.
            Makes the sky blue!
Atmosphere scatters blue light from the sun, making it appear to come from different directions
                        Sunsets are red because less of the red light from the sun is scattered.
Tectonics
            Long cliffs indicate that Mercury shrank early in its history.
Mars versus Earth
            50 percent earth’s radius, 10 percent Earth’s mass
            1.5 AU from the sun
            Axis tilt about the same as earth
            Similar rotation period
            Thin CO2 atmosphere: little greenhouse
            Main difference: mars is SMALLER   
Seasons on mars are more extreme in the southern hemisphere because of its elliptical orbit.
Seasonal winds on Mars can drive huge dust storms
The surface of Mars appears to have ancient riverbeds
Magnetic field may have preserved early Martian atmosphere.
Solar wind may have stripped atmosphere after field decreased because of interior cooling.
Cratering on Venus
            Impact craters but fewer than the moon, mercury, and mars.
            Many volcanoes
            Fractured and contorted surface indicates tectonic stresses.
Most of earths major geological features can be attributed to plate tectonics, which gradually remakes earths surfaces.
Venus does not appear to have plate tectonics.
Venus is so hot because of a runaway greenhouse effect.
Venus has a very thick carbon dioxide atmosphere with a surface pressure 90 times that of earth.
Thick carbon dioxide atmosphere produces an extremely strong greenhouse effect.
Reflective clouds contain droplets of sulfuric acid.
The runaway greenhouse effect would account for why Venus has little water.
Idea of continental drift was inspired by puzzle like fit of continents.
Mantle material erupts where seafloor spreads.
Changes in earth’s axis tilt might lead to ice ages.
Widespread ice tends to lower global temps by increasing earths reflectivity.
Human activity is driving many other species to extinction.
Human use of fossil fuels produces greenhouse gases that lead to global warming.
Located at an optimal distance from the sun for liquid water to exist.