The Dynamic Earth Chapter 3

Earth as a System  Geosphere – land 6,378 km radius  Atmosphere – mixture of gases, air  Hydrosphere – water covers 2/3’s  Biosphere – life exists, 9 km above to the bottom of the ocean

Earths Interior  Each layer of the earth gets denser the deeper it gets  Three Compositional Layers:  1. Crust – outer layer, 5-8km under the oceans, 20-70km under the continents  2. Mantle – 2900km thick, medium dense 64%  3. Core – radius of 3400 km, most dense

The Geosphere

Five Physical Layers of the Earth  Lithosphere – cool, rigid layer, up to 300 km, makes up the pieces called the tectonic plates  Asthenosphere – plastic, solid layer of mantle that flows smoothly and the tectonic plates move on top of it, 250 km  Mesophere – lower part of the mantle, 2550 km  Outer Core – made of liquid nickel and iron, 2200 km  Inner Core – 1228 km, solid nickel and iron

Plate Tectonics  Continents are on the tectonic plates and move with them  Major tectonic plates are the Pacific, North American, South American, African, Eurasian and Antarctic  Geologic activity occurs at the boundaries between tectonic plates  Plates collide, pull apart, slip past each other cause mountains to form, earthquakes and volcanoes

Earthquakes  Fault – break in the crust that is where earthquakes occur  Richter scale measure of the magnitude of an earthquake, each number is 31.7 times stronger than the number below Volcanoes  Ring of Fire Contains 75% of the worlds active volcanoes  Located on plate boundaries

Erosion  Removal and transport of surface material  2 Types:  Water Erosion – rivers and oceans  Wind Erosion – deserts and beaches

Atmosphere -  Mixture of gases surrounding earth  Constantly changing  Insulates thus keeping earth temperature constant  Nitrogen makes up 78%  O, Ar, Co 2, methane, water vapor  Atmospheric Dust-soil, salt, ash from fires, volcanic ash, pollen, bacteria, viruses  Air pressure is less dense the further out

Atmosphere – 4 layers 1.Troposphere – area closest to the ground, 18 km 75%of the gases, dust, ice and liquid water-Weather, Clouds, and smog occur here 1.Troposphere – area closest to the ground, 18 km 75%of the gases, dust, ice and liquid water-Weather, Clouds, and smog occur here  2. Stratosphere – km Ozone layer, temperature rises  3. Mesosphere – km, coldest layer, down to -92 o C  4. Thermosphere – contains the ionosphere where electrical charged particles are (get AM radio at night when sun goes down, particles quit jumping)  Temperatures up to 2000 o C 2000 o C2000 o C

 Energy Transfer occurs by:  Radiation – electromagnetic waves, no contact but still feel it, moves from object with a higher temperature to one with a lower temperature  Conduction – direct contact, fast moving molecules to slow moving molecules  Convection – density differences, air is warmed, the air molecules move apart which increases the volume of air which reduces its density thus the air raises and causes a circular movement of air called a convection current

Green House Effect  Solar energy is trapped next to the earth’s surface by the atmosphere  Gases that trap heat next to earth are called greenhouse gases: water vapor, carbon dioxide, methane and nitrous oxide  These gases keep earth warm enough to support life as we know it.

Water Cycle

Water on Earth  Hydrosphere – all water on earth’s surface, covers 70% of earths surface, 97% salt water, of the remaining 3% - 2/3’s is frozen in the ice caps of the south and north poles  Water Cycle – water constantly moves between the atmosphere and earth, sun provides the energy for this –Evaporation - Heat from sun cause water to evaporate into the atmosphere into water vapor –Condensation -Water vapor changes back into a liquid in the atmosphere as it cools, when it condenses it forms clouds –Precipitation – clouds cannot hold any more water vapor, it falls as rain, snow, hail, sleet  rain is either absorbed by ground, runoff, or evaporates

Earth’s Oceans  Make up over 70% of the earth’s surface  Major Oceans:  Pacific Ocean is the largest – deepest area of all ocean is Challenger Deep, 11,033 m below sea level, (deeper than Mt. Everest)  Atlantic Ocean- also North and south  Indian Ocean  Arctic Ocean – smallest ocean covered by ice, pack ice

Ocean Water  Salinity – concentration of all the dissolved salts, average 3.5%  Composed of Sodium (31%) and Chlorine (55%)  Zones of the Ocean  Surface Zone – warm, sunlight  Thermocline – area that gets cold  Deep Zone – average temperature 2 o C  Functions to absorb and store solar energy  Currents move warm and cold water

Biosphere  Closed system – matter in the environment  Open system - for energy, sunlight