1.1 The Earth’s Atmosphere supports life:
ATMOSPHERE:
--the layer of air that surrounds the earth’s surface
--composed mostly of 4 gases: N (78%), O (21%), CO and Ar (trace)
--these gases are usually constant from the surface of the earth to approx.
25 km.
--through the use of the above gases, such processes like respiration,
photosynthesis, and evaporation take place
--the atmosphere also consists of water vapor and dust
Major Gases (gases with total composition >1%)
Nitrogen…essential to living things; proteins contain nitrogen; nitrogen helps in growth
and repair of body cells; we don’t get much of our nitrogen from air, but plants and
animals that we eat
Oxygen…we take oxygen directly from the air and use it to release energy from our food
in a usable form; oxygen is used in a lot of other processes…any fuel uses oxygen as it
burns…gas in cars, candles on cakes; some reactions are fast and some are
slow…matches are fast, steel with oxygen to make rust is slow
Trace Components (gases with total composition <1%)
Carbon Dioxide…essential to life; plants use it to produce food, animals give it off as
waste; when fuels like coal/gas are burned, carbon dioxide is released which increases the
earth’s temperature/global warming
Trace Components’ percentages…
Argon ( )
Carbon Dioxide ( )
Neon ( )
Helium ( )
Methane ( )
Hydrogen ( )
Carbon Monoxide ( )
Ozone ( )
Nitrogen Dioxide ( )
Sulfur Dioxide ( )
Natural processes modify the atmosphere.
Carbon Cycle:
Nitrogen Cycle:
Water Cycle:
1.2 The sun supplies the atmosphere’s energy.
Radiation: transfer of heat energy through empty space by waves
(ie…
)
Conduction: transfer of heat energy from one substance to another by direct contact
(ie…
)
Convection: transfer of heat energy in fluid form, gas or liquid
(ie…
)
The atmosphere has temperature layers.
THERMOSPHERE: --farthest layer of our atmosphere from the earth’s surface
(thermo = heat)
--thin air/few particles of dust or water vapor
--mostly composed of H and He; N and O also present
--upper portion is very hot due to solar radiation (up to 1800 C)
--no accurate measurements to define the top of this layer due to
the thin-ness of the air
--extends from approx. 90 km. to…
Thermosphere is broken into two layers…
Ionosphere (approx. 90 km. – 550 km.)—solar energy causes gas molecules to become
ions…examples include radio waves and Northern Lights, which are caused by particles
of the sun striking N and O ions to glow
Exosphere (approx. 550 km. - ???)—satellites (TV, weather) and long distance phone
signals
MESOSPHERE:
(meso = middle)
--the second highest layer of the atmosphere
--mostly composed of O and N
--top portion has temps below freezing = coldest part of the atmosphere
--approx. 50 – 90 km. above earth’s surface
--very thin air
--protects earth against meteors/shooting stars as they burn here
STRATOSPHERE:
(strato = layered or
spreading out)
--portion of the atmosphere extending from approx. 11 – 50 km.
above the earth’s surface
--thin air, little moisture
--ozone (molecule created by 3 oxygen atoms) formed when lightning
interacts with oxygen; the upper strato- is warmer than the lower stratodue to the ozone layer, which absorbs energy from the sun and warms the
air
TROPOSPHERE:
--bottom layer, containing most of the earth’s gases
(tropo = changing or --conditions are more variable than in other layers
turning)
--contains all earth’s weather systems (clouds and winds)
--approx. 10 km. thick
--gradually increasing temps as descending toward the earth
--gravity as quite an effect