b. Composition of the Atmosphere Gas % Importance for atmosphere / climate & Life N Oxygen 78.09 20.95 Used in Proteins Respiration Water Vapour 4.0 Cloud formation, reflects and absorbs radiation keeps temps constant. Used by life after circulated by H20 cycle CO2 0.03 Absorbs long wave-length radiation. Increases global temps via natural greenhouse effect. Anthropogenic release increases this risk. Used in Photosynthesis O3 0.00006 Absorbs incoming solar radiation is a greenhouse gas Argon 0.93 None Dust Trace Absorbs and reflects radiation. Volcanic eruptions release it. Form condensation nuclei for cloud formation Pollutant Gases SO2, NO, CH4 Affect levels of incoming solar radiation and cause acid rain Chemoautotrophs use CH4 as a source of C. Still important in deep oceans

‘Dynamic Equilibrium’: Exists in the atmosphere where composition only changes over very long timescales. Photosynthesis Respiration Respiration Photosynthesis Rates of P and R vary over different timescales so concentrations of C02 fluctuates

‘Temporal Changes in the Atmosphere (Changes with Time)’: (i) CO2 changes in a 24h cycle. How and Why? (ii) CO2 fluctuates more in summer. Why? (iii) Water vapour varies too…. Why? (iv) Gases can change in the longer term…. Why?

‘Changes in the Atmosphere with altitude (Height): (i) Why does ozone (O3) naturally increase in the stratosphere? (ii) Why does the temperature decline with rising altitude in the troposphere? This helps produce the layered structure you have seen.

Solar Radiation and the Atmosphere (i) Explain how solar radiation heats the atmosphere? (p.80). Use a diagram next to summarise the heat budget of the atmosphere. (ii) Get all of the key terms for your notes. Nuclear Fusion. / Electromagnetic Radiation Global Climate Change (iii) Draw a diagram using Waugh to show the percentages of total radiation entering the atmosphere

How the sun heats the Atmosphere Sun: Incoming solar radiation (Short Wavelength) The atmosphere is heated in two ways Thermosphere Mesosphere Is warmed directly by absorption by O3, water vapour, C02 and Ice and Dust (‘TOP DOWN’) Stratosphere Troposphere Most (94%) of atmosphere is heated ‘bottom up’ by heat energy that is radiated from the ground surface Ground