the state of the atmosphere at a given time and place

depends on:

•amount of clouds•temperature

•air pressure •wind

•amount of moisture

•A thick blanket of gases surrounding the Earth

•composed of AIR (a mixture of gases)

•Makes conditions on Earth suitable for life

Nitrogen (N) 78%

Oxygen (O) 21%

Also, Carbon Dioxide (CO2), H2O Vapor, and Argon (Ar) in small amounts

Nitrogen

•Essential to living things•Used to grow & repair cells

•Cannot obtain N2 from the air-bacteria fix nitrogen in soil for use

Oxygen

•Essential to living things & some non living

•Combustion•Oxidation (rusting)

•Molecule O2 or O3

3 oxygen atoms bonded together

O is an atom of Oxygen (O)

O2 is atmospheric Oxygen (O-O)

O3 is ozone (O-O-O)

•Absorbs 99% of harmful ultraviolet rays from the sun

•ozone layer is about 10 to 20 km thick

•thinning is the result of chloroflorocarbons (CFC’s) containing chlorine, fluorine, and carbon

Carbon Dioxide•CO2

•Essential to life•Plants rely for food•Animals-waste product•Released during combustion•Excess may contribute to

global warming

Water Vapor•Water as a gas H20

•Invisible•Amount varies by time & place•Forms clouds during

condensation

Particles in Air•Air in nature is not pure•Contains tiny particles of:

•Dust•Smoke•Salt

Smog

•Smoke & fog•1st used to describe air

pollution produced by burning coal during the IR in London

Houston on a smoggy day (left) and a clear day (right).

Pollutants• Harmful substances in air, water, or

soil• Higher concentrations in larger cities• Some natural• Most by human activity: Burning

fossils fuels such as: Coal, Oil, Gas, Diesel– ½ from cars & other vehicles– Factories & power plant

Natural Sources

• Salt Spray• Plant pollen• Forest fires• Soil erosion• Dust storms• Volcanic eruptions

Human Activity

• Burning fossil fuels• Photochemical smog: photo-

meaning “light” caused by sunlight on chemicals– Nitrogen in the warm air reacts

w/burning hydrocarbons – Irritates breathing, harms plants,

damages rubber, paint, & plastics

Acid Rain• Forms when nitrogen oxides &

sulfur oxides (produced from burning fossil fuels) combine w/water in the air

• Can harm trees, pollute ponds & lakes, & kill small organisms (fish, amphibians, insects, & plants)

Improving Air Quality

• Laws & regulations for filters on:– Cars– Smoke stacks

• Filters called “scrubbers”• More fuel efficient vehicles • Public transportation