2Things to think about Look at the world map Earth’s surface is not smooth. What do you think causes variations in its surface?Is the Earth changing? List any evidence (features or processes) that it is or is not changing.What changes might occur to Earth’s surfaceOn a time scale of 100 yearsOn a long time scale (10,000 – 1,000,000s)
3USGS recent earthquakes The above link is to recent earthquakes
4What does the pattern of earthquakes and volcanoes suggest? How about the shape of the continents?
11More evidence of continental drift The colored bands represent where fossils of different critters and plants have been found.They span two or more continents.These creatures do NOT swim—or they are freshwater animals—so the continents must have been connected
22Ocean water96.5 % H2O by massRemainder: various salts [35 parts per thousand]Temperature:Warmer near the surfaceDeep water (below ~1000 m) is equally coldDensity:Colder, saltier water is denser = deep water
23Salinity patterns number is “parts per thousand”
24Ocean currents Water flows horizontally Causes? Surface: windDeep: density differences – salinity, temperatureOcean conveyor - YouTube
25Vertical movements Upwelling Deep, cold water rises to replace surface waters that flow awayBrings nutrients to surfaceSite of rich fisheries
26FreshwaterReview: Where is the freshwater on Earth, and in approximately what percentages?Ice caps, glaciers: 69 %Aquifers: 30 %Surface water: 0.9%Atmosphere (and biosphere): 0.1%
27AquifersRock layers below the surface of the earth that are porous and hold water.Water moves through an aquifer just as water moves in a river.
30How water moves in aquifers In a word:SLOWLY!Depends on the size of the pore spaces.Smaller spaces mean slower flowAt the other extreme: Large ``pore’’ space of a cave might have a river run through it
31Aquifers Supply drinking water Anyone who has a well gets water from an aquiferAbout HALF of all Americans get most of their water from wellsRECHARGE is key—the infiltration of water back to the aquifer
32Aquifers Is the water clean? Water moving through pore spaces of rock or gravel is naturally filtered``coffee filter’’ keeps coffee grounds behindDissolved chemicals can contaminate an aquifer and water pumped from its wells.The filter doesn’t prevent the ``coffee’’ from going through
44Where did the atmosphere come from? May have developed from gases released by volcanoes.This is Kilauea in Hawaii.Early atmosphere very different from today.NO O2, but H2O, CO2, CH4, HCl
45Composition Nitrogen – 78 % Oxygen – 21 % All the rest??? Carbon dioxide, methane, CFCs,Water vapor is variable, from 0 to %
46Structure 4 major layers Troposphere: where the weather is Tropopause: jet streamStratosphere: ozone layer99% of the total mass of the atmosphere is below 32 kmTemp. drops 5-10 C every 1 km in troposphere
47Impact of air density Where is air densest? Where is it least dense? How does this affect a batted baseball?
48NOT true any longer: air conditioners and refrigerators no longer contain CFCs BUT: CFCs last a long time in the atmosphere (decades) so these gases are still doing damage.
49Troposphere Our sphere Weather Notice: patterns TemperatureWindsLayer ends when temp. no longer varies with height = tropopause
50Water cycleConnects ocean and atmosphereKey pt: what happens in the atmosphere depends a lot on what happens in the ocean
51Solar energy Energy from sun Some absorbed by gases (O3, H2O) Some reflected by clouds and by the Earth’s surfaceLast is called albedo
52albedo Notice snow, water, and clouds What feedback effects would you expect from melting of ice caps?
54Energy transferSimplified earth: slow rotation to east, no interaction of oceans and landSun warms equator, air rises, spreads north and southCold air at poles sinks and replacesAir deflected by rotation, to right in N hemisphere, to left in S hemisphereCoriolis effect