Weather World Geography Notes 1.5. Atmosphere Atmosphere is a thin layer of gases This protects the surface from Temperature extremes (acts as insulation)
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AtmosphereAtmosphere is a thin layer of gases
This protects the surface from Temperature extremes (acts as insulation)Space debrisDangerous radiation
Gravity holds Earth’s atmosphere
Nearly all atmospheric gases are contained within around 20 miles of Earth
Weather occurs within 10 miles
CompositionOxygen and Nitrogen make up 99% of dry air
This excludes water vapor
Nitrogen comprises 78% of the atmosphere
Oxygen comprises 21% of the atmosphereVital to respirationActive agent in weathering
Weather and climate are not affected much by nitrogen or oxygen.
The variable gases that are most important to weather and climate are:Water vaporCarbon dioxide
Water vapor is the most variable: May make up .1% to 4% of the lower atmosphere’s
volume
It is affected by: Exposed surface water Atmospheric temperature Altitude
Water vapor is critical in: The process of condensation and precipitation Transporting heat around the world through latent
heating
Carbon dioxide is the other very important gas in weather and climate.On average makes up .035% of the atmosphereCarbon dioxide levels decrease in the summer
when plants turn it to oxygen and carbonCarbon dioxide and other gases play an important
part in the greenhouse effectWhich heats the Earth
In addition to gases, Earth’s atmosphere also contains aerosols and particulates.From natural and industrial processesLight enough to stay suspended in the airCan significantly affect weather and climate
Can reduce the amount of energy Earth receives from the sun Can lead to short term global cooling
Also can act as nuclei for condensation of cloud droplets
PollutionThese aerosols, particulates, and atmospheric
gases become pollutants when:Their concentrations increase to levels that threaten
the health of living thingsSubstantially change existing atmospheric conditions
Earth’s Radiation BalanceEarth maintains a radiation balance:
Energy coming from the sun must eventually be equaled by energy radiated and reflected from Earth.
This process helps explain weather patterns
Solar RadiationThere are different types of radiation that are
identified by their wave lengthThe distance between wave crests
Visible light ranges in wavelength 0.4 microns to 0.7 microns
InsolationInsolation is a stream of radiant energyOnly about 52% passes through the atmosphere to
reach Earth’s surface. The atmosphere: absorbs (~23%), reflects (~17%), and
scatters (~8%)
Reflection of insolation is determined by an objects albedo (reflectivity)
On average about 52% of insolation reaches Earth’s surface where it is:Reflected orAbsorbed and converted to kinetic energy
This creates and moves weather
Albedo can range from 3% to 95%Water has an albedo of 3% to 10%, but has a higher
albedo as it approaches the poles (nearly 100% in some cases)
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