The Atmosphere

Thin layer of gases surrounding the Earth, held in place by gravity

provides life support systems - absorption of EM radiation from Sun - gas resources for natural processes - heat distribution - delays escape of infrared energy - creates ocean currents - water vapour transport

Nitrogen 78% Oxygen 21% Carbon dioxide 0.04% Rare gases 1% Methane 0.00017% Water Vapour up to 4% Ozone 0.000007%

Carbon Nitrogen Oxygen Hydrogen

Gases that are better at absorbing infrared than the average for the atmosphere

• Visible light passes easily through the atmosphere • It gets absorbed the the Earth’s surface, warming it up • Warm Earth’s surface emits infrared radiation • Infrared cannot pass through the atmosphere as easily because it is absorbed by the greenhouse gases. • They reemit. The cycle continues.

Solar Emissions Greenhouse Gases

• they are increasing very slowly • there is a short term 11 year cycle of varying solar output

a) bacteria in soils b) bacteria in soils c) evaporation d) photosynthetic organisms e) stratosphere only

a) hospitals and welding (possibly) b) evaporation from power station cooling towers

• more released by humans does not increase max humidity unless temp increases because it will precipitate • climate change causes temps to increase = max humidity increases • concentration is balanced by evapotranspiration and condensation. Both controlled by temp. Changing temp changes concentration

Burning fossil fuels and wood Ploughing soil Draining marshes/bogs

Anaerobic respiration by microbes in padi fields/intestines of livestock/landfill sites Creation of fossil fuels Release from coal mines Leaks from natural gas fields/pipelines

Reaction of oxygen and nitrogen at high temps (engines and power stations) Then released by exhausts Fertilisers

Aerosol propellants Coolants in fridges Fire extinguishers Expanding foam plastics Solvents

Nitrogen dioxide breaking down with light then reacting with oxygen

a) 1 b) 25 c) 160 d) 25,000 e) 2,000

a) source of energy for chemoautotrophs b) hydrological cycle and insulation as a GG c) synthesis of proteins d) insulation as a GG and reactant for photosynthesis. synthesises lipids, carbs and proteins e) respiration f) absorbs harmful UV dangerous to life

• natural processes are in balance: change only happens over a very long time

Photosynthesis Respiration • roughly balance each other out but rates vary over different timescales causing gas fluctuations around their mean concentration

a) Early hours = more as it is dark so respiration outweighs photosynthesis Middle of day = less as the increased light allows photosynthesis. Later = more, gets darker… b) January-April = respiration outweighs photosynthesis so concentrations are high April-August = photosynthesis levels high so concentration decreases August-December = respiration outweighs photosynthesis so concentrations are high

If one process is changed, other processes can change - it means human actions can trigger a chain reaction of altering processes as a direct response to the first change - not possible to accurately predict the impact on specific processes yet though as there is a lot to be discovered.

Troposphere Stratosphere Mesosphere Thermosphere

Majority of atmosphere is near the ground - 80% of gases are in the troposphere which is within 10km of surface gradually gets thinner up to about 10,000km - considered the upper limit of the atmosphere