DE (W1&2)

• earth is an open system
• the earth system consists of the atmosphere, biosphere, hydrosphere, cryosphere and lithosphere
• an open system allows transfer of mass and heat, a closed system only allows the transfer of heat and an isolated system does not allow the transfer of either
• the earth system is driven by two energy sources, external energy and internal energy
• there are three types of internal energy: primordial heat (heat from when the planet formed), radioactive decay (heat generated by the decay of one element into another), and gravitational heat (heat generated from movement/friction as materials sink due to gravity).
• incoming solar energy must be equal to the outgoing energy released by the earth to maintain a stable temperature
• the sun emits energy in the form of shortwave radiation
• the earth emits radiation in the form of longwave radiation
• the sun is hotter than the earth and is therefore more energetic
• why does the sun emit short wave radiation?

  it is extremely hot and has a lot of energy to give off and energy is inversely proportional to wave length
• Weins Law states that the type of radiation emitted by an object depends inversely on the absolute temperature of that object
• Stefan Boltzmann Law states that the amount of radiation emitted (energy flux) is related to the 4th power of the absolute temperature of the object
• the sun emits more radiation than the earth (energy flux) due to having a higher temperature
• there are two types of seismic waves, compressional and shear waves
• compressional waves cause expansion and compression when travelling through the earths layers, it can pass through solid, liquid and gas
• shear waves cause side to side movement and can only travel through solids
• the inner core is solid and is made of almost pure iron and nickel
• oceanic crust is thinner (7km thick) than continental crust (40km thick)
• continental crust is less dense than oceanic crust and 'floats' on the mantle
• the crust is made up of low density silicate
• the mantle is the largest part of the earth's interior and makes up about 84% of its volume
• the outer core is molten liquid and is made up of 90% iron and nickel with 10% being lighter elements eg. oxygen and sulphur
• 90% of earth's mass consist of just four elements - Iron, Oxygen, Magnesium and Silicon
• the continental crust rides higher than the oceanic crust as it is less dense, this is what causes the difference in elevation between the continents and the sea floor
• the upper part of the mantle can glue itself to the crust, forming a layer called the lithosphere, that behaves structurally as one
• mechanical strength - is the material weak or strong and how does it deform
• the Lithosphere (10-200km deep) is solid and rigid
• the Asthenosphere (to a depth of 660km) is ductile and weak, but still solid
• the mesosphere is the lower part of the mantle (to a depth of around 2900km). It is rigid
• energy from the sun is emitted in three forms, half as visible light, while the other half is split between infrared waves and ultraviolet waves
• infrared waves emitted from the sun have longer wavelengths and lower energy intensity than visible light and is perceived as heat
• ultraviolet waves have shorter wavelength and higher energy intensities than visible light
• Earth maintains a radiation balance: an equilibrium between incoming and outgoing radiant energy. If equilibrium is disrupted the surface of earth will heat up or cool down
• the fraction of solar energy reflected by a surface is called its albedo
• what is the Earth's albedo?

  29%
• types of greenhouse gases include; water vapour, carbon dioxide, methane and ozone.
• the greenhouse effect is the trapping of heat by greenhouse gases in the atmosphere which increases the surface area of Earth relative to the temperature higher in the atmosphere
• How much warmer is the Earth than it would be if there were no greenhouse gases in the atmospher?

  33 degrees Celsius
• there are two types of feedback in systems: positive feedback which change in one component is enhanced by changes in other components and negative feedback, in which a change in one component is reduced by changes in other components.
• the mantle is layered between the upper and lower mantle, separated by a transition zone where the rock density increases in a series of steps