The Changing Atmosphere

 

Origin of the atmosphere

·       Our original (first) atmosphere was only Hydrogen and Helium ~4.6 b.y.a.

o      Escaped from Earth’s gravity

·       Volcanoes formed our early  (second) atmosphere

o      Volcanoes spew out large amounts of CO₂, Nitrogen and water vapor

o      CO₂ warms the atmosphere by absorbing outgoing heat (early Earth was warmer)

o      Earth’s core then cooled- volcanic activity decreased- water vapor formed clouds- rain from clouds formed rivers, lakes, oceans- marine plants produced oxygen

§       This led to oxygen in our atmosphere and a decrease in CO₂ (since plants now needed it)

§       Earth then cooled

Dirty Air: Smog

·       A type of air pollution caused by human activity

o      Caused by the burning of fossil fuels (like gasoline, coal)

·       2 types of smog

o      Gray Air

§       Colder, moist climates

§       Pollution + moisture forms a grayish haze

o      Brown Air

§       Warm, dry, sunny climates

§       Pollution reacts with sunlight to form brown haze

·       Aka Photochemical smog (b/c needs sunlight)

·       Both cause health problems

o      Burning eyes

o      Headaches

o      Respiratory problems

 

 

The Greenhouse Effect

·       Traps energy from the Sun to warm the atmosphere

o      CO₂ and some other gases absorb the infrared radiation that is reflected from the Earth’s surface.  This keeps the Earth warm by forming a “heat blanket” around the Earth

·       Greenhouse Effect is a good thing

o      Without it Earth would freeze

o      Too much = planet Venus!

·       Amount of CO₂ in the atmosphere has been rising

o      Causes temperatures to increase

§       Global Warming

·       Could change Earth’s climate

·       Scientists predict temps will rise 4-6° over the next 50 years

o      Caused by increase human activity sending out more CO₂

Ozone Depletion

·       Overexposure to UV rays cause health problems

o      Sunburn

o      Cataracts

o      Skin cancer

·       Chlorofluorocarbons (aka CFC’s)

o      Destroy ozone layer

o      Breaks apart the bond of 3 oxygen molecules (which is ozone) and then no more ozone

o      Found in air conditioners, Styrofoam, aerosol cans, etc.

·       Ozone layer has been thinning

o      Allows more UV rays to reach Earth’s surface

·       Clean Air Act

o      Bans CFC’s so we won’t destroy ozone

o      Replaces CFC’s with ozone friendly materials