Structure of the Atmosphere

• What are the five layers of the atmosphere?

  troposphere, stratosphere, mesosphere, thermosphere, exosphere
• What is the earths gas composition?


  78% nitrogen

  21% oxygen

  1% other gasses; argon, carbon dioxide, neon, helium, methane
• How are the layers identified?


  -thermal change

  -chemical composition

  -movement

  -density
• What are the borders of each layer of the atmosphere called?


  The layer before + pause

  - tropopause
• Troposphere


  -lower atmosphere

  -all weather occurs

  -warmed by infrared radiation carried by convection currents

  -air become thinner as you go up

  -temperature and pressure decreases as you go up
• Stratosphere


  -holds 19% of gasses but very little water vapour

  -temperature increases with altitude, heat is produced from the formation of the OZONE

  -no 'weather' always sun and calm

  -planes fly in this layer as there is little turbulence
• Ozone


  -chemical symbol O3

  -is poisonous, a hazard in the troposphere

  -ozone absorbs UV radiation

  -thinning and holes are a concern as more UV can get through
• Mesosphere


  -gasses are thick enough to slow down meteors

  -middle atmosphere

  -contains charged particles which absorb harmful gamma rays and UV radiation -> northern and southern lights

  -particles reflect radio waves, allowing radio signal to travel around the earth
• Thermosphere


  -high energy ultraviolet and x-ray radiation from the sun are absorbed, causing large temperature changes

  -contains charged particles which absorb harmful gamma rays and UV radiation ->northern and southern lights

  -radio waves are also reflected, so radio signals can travel earth
• Exosphere


  -outermost layer

  -atoms and molecules escape into space and satellites orbit the earth
• Role of the Atmosphere


  -Supplies oxygen we breathe and carbon dioxide for plants

  -Shields Earth from UV rays (ozone layer)

  -Acts as a blanket to hold in heat (greenhouse gases) and redistributes heat across the globe (wind circulation)

  -Helps maintain the hydrologic cycle

  -Reduces extreme temp changed from day to night
• Dynamic equilibrium, in the atmosphere


  Maintains the average composition of the atmosphere, changes over a very long time

  Processes used- photosynthesis and respiration
• When does each process of the dynamic equilibrium happen?


  Night- co2 increase, oxygen decrease

  Day- co2 decrease, oxygen increase
• Processes that alter the composition of the atmosphere


  -photosynthesis

  -Combustion

  -Respiration

  -Transpiration

  -Evaporation

  -Nitrogen fixation
• Distribution of earths energy given by the Sun


  -The atmosphere (clouds, aerosol, water vapour, and ozone) directly absorbs, about 23% of solar energy

  -Evaporation and convection, transfers, 25% and 5% of solar energy from the earths surface to the atmosphere
• Radiation


  The transfer of heat energy through space by electromagnetic radiation
• Conduction


  The transfer of heat energy from one substance to another, or within a substance
• Convection


  The transfer of heat energy in a fluid
• Barometer


  An instrument that measures atmospheric pressure- unit, atmospheres
• Feedback mechanisms


  -nitrogen and carbon cycles

  -movement of elements between the atmosphere, biosphere, lithosphere and hydrosphere
• Natural greenhouse effect


  The sun radiates UV to the earth, most is absorbed by the earth and the rest is reflected back into space. The absorbed energy is turned into infrared radiation and re-emitted back out. Molecules in the ozone layer absorb the radiation, keeping the earth warm.