3-2 The Atmosphere

The Atmosphere• A mixture of gases surrounding

the earth– Insulates the earth, maintaining a

temperature that allows living things to survive

composition• Nitrogen – 78%• Oxygen – 21%• Other – 1% ( argon, CO2, methane CH4, H2O)• Solids: dust, soil, salt, ash, skin, hair, pollen, • bacteria, viruses, aerosols (liquid droplets)

Pressure

• Atmosphere (gasses have mass) pulled toward earth by gravity

• Atmosphere is more dense near the surface• Pressure decreases as you increase altitude

Layers of Atmosphere (4)-based on temperature changes

• Troposphere – nearest the earth to 18 km– Site of weather–Most dense layer– Temperature decreases as altitude

increases

Layers of Atmosphere

• Stratosphere – 18 km – 50 km– Temperature rises as altitude rises– Contains ozone layer (traps UV energy & warms

the air). Ozone O3

Layers of Atmosphere

• Mesophere – 50 km – 80 km– Coldest layer -93 degrees C

Layers of Atmosphere

• Thermosphere – 80 km – 550 km– Temperatures above 2000 degrees C. N & O

absorb solar radiation. Not hot, because molecules do not strike each other & transfer heat.

– N & O absorb radiation & become charged (ions) Ions radiate light forming aurora borealis

(Northern Lights)

Energy in the atmosphere• How is energy transferred in the atmosphere?

• What is energy?

• What forms do energy take?

How is energy transferred?

• Heat likes to move from a heat source to a heat sink.

• Radiation is movement of energy in electromagnetic waves (light)

Energy transferred in 3 ways:• Radiation: across space

• Conduction: flows from warm object to cold

object

• Convection: air currents unequal heating of

atmosphere

Heating the atmosphere

• Solar energy (electromagnetic radiation) travels to earth in waves– 50% reaches the earth’s surface– 5% reflected by the surface of the earth– 20% absorbed by ozone, clouds, gases– 25% scattered & reflected by clouds & atmosphere

Movement of air

• Convection current causes weather

Greenhouse effect

• Gases in atmosphere (CO2, CH4, H2O, nitrous oxide) trap light energy & warms the air,

radiating heat back to earth

• Loss of greenhouse gases would cause earth to cool

• Increases in CO2 cause earth to warm (global warming)

http://mrsdlovesscience.com/greenhouse/greenhouse_effect.jpg

http://www.bing.com/url?source=images&rch=Qm2q_8PEbmZSNQVNGheVdhD9RcYDHNf&url=http://www.climatechangenorth.ca/images/illustrations/HS_2-3.gif&urltarget=_blank&q=Nitrogen+Animation&view=detail&id=BACD06CAB0869018F2A879657D1CA27BECEF6435&first=61&FORM=IDFRIR&ssIG=de6d041dff9f42ce9a477c1ec6aa8965