Date post: | 26-Dec-2015 |
Category: |
Documents |
Upload: | ross-tyler |
View: | 213 times |
Download: | 0 times |
Review Question 1In your own words, what is Geography?
BAD answer:The science that studies the relationships between natural and cultural systems and the interdependence of the two over space and time
These are not YOUR words!
Review Question 2Why are sunspots darker than the rest of the sun?
A) Because they are hotter than the surrounding surface
B) Because they are cooler than the surrounding surface
C) Because of solar wind
D) Because there is no sunlight on them
Review Question 3When is the subsolar point directly over 20°N latitude?
A) Never
B) Between the summer solstice and the fall equinox
C) Between the spring equinox and the summer solstice
D) B & C
Chapter 3Earth’s Modern Atmosphere
Geosystems 6eAn Introduction to Physical Geography
Robert W. ChristophersonCharles E. Thomsen
The AtmosphereAtmosphereAtmosphere: an envelop of gaseous mixture (also containing suspended solid and liquid particles and clouds) that encircles a planet
Earth’s Modern Atmosphere
The atmosphere is absolutely essential for life on Earth
Earth’s atmosphere exists in a series of spheres or layers that grade into one another
Composition, temperature, and function
Atmospheric Profile Our atmosphere extends to roughly 32,000 km (20,000 mi) from surface
The top of the atmosphere has no clear boundary
Gravity holds our atmosphere in place
Top of Thermosphere is at 480 km (300 mi) = top of the principle atmosphere
Exosphere
Atmospheric Composition
Two broad regions:Heterosphere – outer atmosphere
80 km (50 mi) outwards, to top of thermosphere Layers of gases sorted by gravity
Homosphere – inner atmosphere Surface to 80 km (50 mi)Gases evenly blendedOzone layer
TroposphereSurface to 18 km (11 mi)
90% mass of atmosphere
Normal lapse rate – average cooling at rate of 6.4 C °/ km (3.5 F°/1000 ft)
Tropopause
Atmospheric Temperature
Atmospheric Temperature
Stratosphere18 to 50 km (11 to 31 mi)
Temperatures increase with altitude
Stratopause
Ozone layer
Atmospheric Temperature
ThermosphereRoughly same as heterosphere
80 km (50 mi) outwards
Altitude varies
Temperatures increase with altitude, but little actual heat
Atmospheric Function
IonosphereAbsorbs cosmic rays, gamma rays, X-rays, some UV rays
OzonospherePart of stratosphere
Ozone (O3) absorbs UV energy and converts it to heat energy
Four Principal Components of AtmosphereNitrogen from volcanic sources
Oxygen from photosynthesis
Argon through radioactive decay of isotopes
Carbon dioxide byproduct of life processes
Composition of the AtmosphereComposition of the Atmosphere
Atmospheric gasesAtmospheric gases
Permanent gasesPermanent gases Variable gasesVariable gases
Nitrogen (~78% of vol.)
Oxygen (~21% of vol.)
Argon (~1% of vol.)
…
Water vapor (0-4% of vol.)
Carbon dioxide (0.037% of vol.)
Ozone (0.000007% of vol.)
Methane (0.00017% of vol.)
...
Water VaporWater Vapor
The most abundant variable gas (0.25% of total atmospheric
mass).
Added and removed from the atmosphere through the
hydrologic cycle.
A major contributor to Earth’s energy balance and many
important atmospheric processes.
Carbon DioxideCarbon Dioxide
A trace gas accounting for only 0.037% of the atmosphere.
Added to the atmosphere through biologic respiration and
decay, volcanic eruptions, and natural and human-related
combustion.
Anthropogenically related increases in recent decades have
led to great concern with regard to global “greenhouse
warming”.
Removed from the atmosphere by photosynthesis (go to
biosphere).
Carbon DioxideCarbon Dioxide
The steady increase of atmospheric CO2.
Question: the seasonal variation?the seasonal variation?
MethaneMethane
1.7 ppm; increase 0.01 ppm/yr.
An extremely effective
absorber of thermal
radiation emitted by
Earth’s surface; hence
related in the warming of
the atmosphere.
Released to the atmosphere through fossil fuel activities,
livestock digestion, and agriculture cultivation (especially rice).
Variable Atmospheric Components
Natural Factors That Affect Air Pollution Winds – gather and move pollutants
Landscape – mountains and hills can form barriers to air movement or can direct pollutants
Temperature inversions – trap pollutants and do not allow them to be diluted by the atmosphere
Ozone HoleOzone losses in the midlatitudes 6-8% per decade
Alters atmospheric chemistry, biological systems, ocean phytoplankton, fisheries, crop yields, human eye and skin tissue, and human immunity
Ozone hole is not caused by global warming
CFCsSynthetic molecules of chlorine, fluorine, and carbon
Released by aerosol sprays, propellants, and refrigerants
Do not break down naturally or dissolve in water
CFCsWhen CFCs reach the stratosphere, they are split by UV light
The freed chlorine atom breaks apart ozone atoms creating ClO and O2
O2 is transparent to UV radiation