Term
| Earth’s Primary (First) Atmosphere |
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Definition
| Earth's primary (first) atmosphere immediately after accretion 4.57 billion years ago consisted mainly of hydrogen captured from the solar nebula by Earth’s gravity. Bombarding meteorites contributed additional gases such as water vapor, carbon monoxide, methane, and ammonia. |
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| Earth Struck With A Mars-sized Object ~... |
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Definition
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Term
| The moon-forming impact event |
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Definition
| ‘blew’ most of the primary atmosphere back into space |
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Term
| Earth’s Secondary Atmosphere |
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Definition
Intense heating by the Moon-forming impact left Earth with a magma ocean
As the early magma ocean cooled, reactions between water vapor and the magma ‘mush’ (melt + minerals) released H2 and possibly CH4 into the atmosphere
Magma ocean eventually solidified to form a hard basaltic crust on Earth’s surface |
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Term
| Earth’s Secondary Atmosphere(cont) |
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Definition
Continued cooling of Earth led to further development of a secondary atmosphere via three processes:
Water vapor eventually condensed from the cooling atmosphere and rained down on the surface to form the early oceans by 4.4 billion years ago |
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Term
| Continued cooling of Earth led to further development of a secondary atmosphere via three processes: |
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Definition
–Outgassing of bombarding meteorites
–Outgassing of Earth’s interior (major contributor)
–Photochemical reactions involving atmospheric gases and UV radiation from the Sun |
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Term
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Definition
| heavier gases (H2O, CO2, N2) near the surface to form Earth’s secondary atmosphere while lighter H2 and He escaped into space |
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Term
| Photochemical Dissociation Hypothesis |
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Definition
Early atmosphere contained abundant methane, ammonia and water vapor
This early atmosphere was exposed to ultraviolet light from the sun
No ozone layer back then, so ultraviolet light reached the surface of the early earth |
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Term
| 1. Dissociation of water vapor to hydrogen and oxygen with hydrogen escaping into space: |
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Definition
| 2H2O + uv light = 2H2 + O2 |
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Term
| 2. Newly formed oxygen reacted with methane to form carbon dioxide and water: |
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Definition
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Term
| 3. Oxygen also reacted with ammonia to form nitrogen and water: |
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Definition
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Term
| Two Sources of Free Oxygen (O2) in Earth’s Early Atmosphere |
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Definition
Photochemical dissociation
Ancient photosynthetic cyanobacteria: |
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Term
| Photochemical dissociation |
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Definition
–Eventually all the methane and ammonia were converted to carbon dioxide and nitrogen
–Excess oxygen (O2) started to accumulate as more water vapor dissociated |
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Term
| Ancient photosynthetic cyanobacteria: |
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Definition
First appeared ~3.6 billion years ago
–Released oxygen as a byproduct |
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Term
| Photosynthetic cyanobacteria that first appeared |
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Definition
| ~3.6 billion years ago released oxygen (O2) into the oceans and atmosphere |
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Term
| Over time, oxygen in atmosphere continued to increase: |
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Definition
–Aerobic bacteria appeared by ~2.0 billion years ago as anaerobic forms sought oxygen-poor environments
–Stratospheric ozone layer gradually began to develop and was likely in place by 400 million years ago |
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Term
Using chemical composition, the modern
atmosphere is divided into two broad regions: |
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Definition
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Term
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Definition
– Outer atmosphere beginning 80 km above surface
– Less than 0.001% of atmosphere’s mass
– Gases not evenly mixed |
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Definition
Extends from Earth’s surface to altitude of 80 km
– Atmospheric pressure deceases with height
– Uniform blend of gases
– Mostly nitrogen and oxygen |
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Term
| Stable components of homosphere, in order of greatest to least |
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Definition
| N2, 02, Ar, CO2, Ne, He, CH4, Kr, O3, N20, H, Xe |
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Term
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Definition
decreases in
density with altitude |
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Term
| Atmosphere based on temperature |
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Definition
| trophosphere, strat,meso, thermosphere |
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Term
| Atmospheric Temperature Criterion |
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Definition
LAYERS:Thermosphere
–Mesosphere
–Stratosphere
–Troposphere
BOUNDARIES:–Mesopause
–Stratopause
–Tropopause |
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Term
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Definition
Extends from Earth’s surface up to the tropopause
Varies in thickness from 18 km at the equator to 8 km at the poles
Contains 80 to 90 % of the mass of the atmosphere
–Heated at the bottom
–Rising air cools
–It rains or snows and blows |
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Term
| These features of the______cause our weather |
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Definition
| These features of the troposphere cause our weather |
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Term
| Variable Atmospheric Components |
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Definition
The troposphere contains natural and human-caused variable gases, particles and other chemicals
Aerosols like soot has produced a dimming of sunlight reaching Earth’s surface by 4-8%
World Health Organization estimates that air pollution kills ~4.3 million people worldwide |
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Term
| Sources of natural variable gases and materials |
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Definition
| volcanoes, forest fires, plants, decaying plants, soil, ocean |
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Definition
| sulfur oxides, particulates |
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Definition
| carbon monoxide and dioxide, nitrogen oxide particulates |
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Definition
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| methane, hydrogen sulfides |
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| salt spray and particulates |
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Definition
| Human-caused air pollution most prevalent in urbanized regions |
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Term
| Human-caused air pollution most prevalent in urbanized regions |
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Definition
Particulates and aerosols: small particles of dust, soot and suspended pollution
–Combustion of fossil fuels
–Power and industrial plants
–Photochemical smog resulting from interaction between sunlight and combustion products
–Industrial Smog |
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Term
| Natural Factors Affecting Air Pollution |
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Definition
| winds, local and regional landscapes, temp inversion |
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Definition
–Gather and move pollutants
–Movement of pollutants from one country to another can affect international relations |
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| local and regional landscape |
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Definition
–Surrounding mountains and hills can form barriers to air movement
–Volcanoes eruptions can erupt particulates into the atmosphere and lead to acid rain |
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Term
| Temperature Inversion Traps |
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Definition
| Pollution Near The Surface |
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Definition
Photochemical smog developed with the advent of the automobile
Smog results from interaction of sunlight with combustion products in automobile exhaust (mainly nitrogen oxides and VOCs) |
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Definition
–Peroxyacetyl nitrate (PAN) damages plants
–Ground-level ozone
–Nitrogen dioxide (interacts with water vapor to produce nitric acid) |
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Term
| Particulate matter is a diverse mixture of fine particles: |
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Definition
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Term
| WHO established links between PM pollution and poor health: |
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Definition
| –Asthma prevalence in U.S. doubled since 1980 |
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Term
| The sources of carbon dioxide in the troposphere include: |
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Definition
–Volcanism
–Weathering and erosion
–Respiration
–Burning of fossil fuels (the only source we can control) |
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Term
| Clean Air Act legislation (1970, 1977, 1990) resulted in significant reductions of many pollutants: |
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Definition
–Carbon monoxide (-45%)
–Nitrogen oxides (-22%)
–Volatile organic compounds (-48%)
–Particulate matter (-75%)
–Lead (-98%) |
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Term
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Definition
| Extends from the tropopause to a height of 50km above Earth’s surface |
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Term
| Temperatures get warmer going upward. Why? |
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Definition
| Because here the stratosphere absorbs uv light from the Sun to produce ozone |
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Term
| Although ozone is only a trace gas in the stratosphere, it has a beneficial influence on incoming radiation. What is it? |
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Definition
| Stratospheric ozone protects us from incoming uv radiation from the Sun |
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Term
| Most UV Radiation Absorbed By The |
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Definition
| Ozone Layer (Ozonosphere) |
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Term
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Definition
The O-O bond of an oxygen molecule is broken by uv light. The formed O atom reacts with O2 (and for energetic reasons a collision partner M) and forms ozone (O3).
In an analogous way, ozone is destroyed by photolysis, if the O-O bond in an ozone molecule is split by sunlight. In this case the formed O atom reacts with another ozone molecule and forms two oxygen molecules O2. |
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Term
| Ozone in the stratosphere: |
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Definition
| Ozone in the stratosphere: |
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Term
| ignificant thinning of the ozone layer has occurred in |
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Definition
| polar regions over the last few decades |
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Term
| Ozone levels in the atmosphere have been measured in Antarctica since early 1960’s: |
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Definition
–In 1985, it was reported that dramatic thinning of ozone was occurring over the South Pole from September to November
–Hole has grown enormously since 1979
–In 2006, ozone hole over Antarctica covered an area three times larger than the United States |
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Term
| In the 1980’s, average global ozone concentrations declined |
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Definition
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Term
| In the northern hemisphere, Arctic ozone depletion detected between November and April: |
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Definition
–Large depletion over the Arctic 15% below normal recorded in 1993
–Record 45% loss during spring 1997
–40% loss during winter of 2011 described as “unprecedented” by the UN weather agency |
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Term
| Several causes of ozone depletion: |
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Definition
–High-energy particles from solar flares and sunspots bombard our atmosphere and may also affect ozone
–Volcanic gases and ash particles react with ozone to break it down
–Release of CFC’s into the atmosphere |
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Term
In 1974, CFC’s (Chlorine-Fluorine-Carbon) compounds were detected in the stratosphere:
Major sources of CFCs: |
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Definition
–Air conditioning and refrigeration
–Production of foam
–Aerosol sprays
–Solvents in electronics industry |
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Term
| .....can react with 10,000 ozone molecules |
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Definition
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Term
| During the Antarctic winter, polar stratospheric clouds form under dark, extremely cold conditions: |
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Definition
–Strong westerly winds start to circulate around the continent, creating an atmospheric container (vortex) that traps and chills the air
–Low temperatures form cloud particles that trap compounds |
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Term
| During Antarctic spring, emerging sunlight provides energy to drive |
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Definition
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Term
| During Antarctic spring, emerging sunlight provides energy to drive photochemical reactions: |
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Definition
–Melting of polar clouds release trapped compounds
–Compounds take part in chemical reactions that lead to ozone destruction |
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Term
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Definition
In 1987, 24 nations signed the Montreal Protocol:
–Pledged to reduce CFCs by 1999
Target amended five times since then
CFC manufacturing has now been phased out
In 2005, the IPCC (Intergovernmental Panel on Climate Change) summary report suggested that global average ozone depletion has now stabilized:
–Ozone layer expected to begin to recover in the coming decades due to decline in CFC concentrations, assuming full compliance with the Montreal Protocol
–Antarctic ozone layer not expected to return to 1980 global levels until 2050 and be completely eliminated by 2065 |
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Term
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Definition
| The Mesosphere extends from 50 km (at the Stratopause) to 80 km above Earth’s surface |
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Term
| Temperature becomes cool at higher altitudes within the Mesosphere. Why? |
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Definition
–Because of the decreasing influence of ozone
–Mesosphere does not absorb any significant portion of solar radiation |
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Term
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Definition
Extends beyond 80 km above Earth’s surface
Very low pressures (.005mb)
Near the poles, the earth’s magnetic field concentrates the solar wind to form auroras |
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| Temperature increases upward because of interactions with the |
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Definition
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| Temperature increases upward because of interactions with the solar wind: |
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Definition
–Ionization (ionosphere) of atmospheric gases increases with sunlight (daytime)
–At night, shortwave radio waves bounce off ionosphere |
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| Ionosphere is composed of the |
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| the E and F layers bounce the |
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