Earth's Atmosphere Flashcards
What is weather? What factors can impact the weather?
- The state or condition of the atmosphere at a given place and time
- Temperature
- Cloud cover
- Wind speed/direction
- Humidity
- Air pressure
- Precipitation
What is climate?
The average weather over a long period of time
What is meteorology?
The study of the atmosphere
What is the first layer of the atmosphere?
- Troposphere
- Thickest air here
- Weather occurs
- Has almost all the water vapor carbon dioxide in atmosphere- some escapes into stratosphere
- Temp decreases as altitude increases- air heated from below by thermal energy radiating from Earth’s surface
What is the second layer of the atmosphere?
- Stratosphere
- Ozone located here
- Temp increases as altitude increases- air heated from above- ozone absorbs radiation from the sun
What is the third layer of the atmosphere?
- Mesosphere
- Where meteors burn up
- Temp decrease as altitude increases
- Coldest layer of atmosphere
What is the fourth layer of the atmosphere?
- Thermosphere
- Ionosphere located here
- Auroras happen here
- Temp increases as altitude increases- nitrogen + oxygen atoms absorb x-rays and ultraviolet radiation
Ozone layer (location, benefit, threat, helping it)
- Stratosphere
- Ozone- compound composed of 3 oxygen atoms (O3), protects all life by absorbing harmful ultraviolet radiation
- Threat: chlorofluorocarbons manufactured by humans rise into the stratosphere and attack ozone
- CFC contents peaked in the 1990s and now declining- international rules were passed limiting/banning products that used CFCs- contents decreasing
Where/what is the ionosphere? What is its benefit?
- Lower region of thermosphere
- Layer of ions
- Radio waves can bounce off of it
How does air pressure change as elevation increases?
Elevation increases- air pressure decreases
How does the density of the air change as elevation increases?
Density of air goes down with higher elevation
What is the chemical makeup of Earth’s atmosphere?
Nitrogen: 78.1 % Oxygen: 20.9 % Argon: 0.93 % Carbon Dioxide: 0.04 % Water Vapor: 0.01 - 4.5 % Helium, ammonia, neon, methane
What is the composition of Earth’s early atmosphere (after asteroid impacts)?
- No free oxygen
- Water vapor
- Nitrogen
- Carbon dioxide (100-1000 times more than we have today)
What was the chaotic history of Earth’s early atmosphere?
- First atmosphere composed of nebula gases (hydrogen, helium, methane, ammonia) obliterated by asteroid impacts
- Earth’s gravity too weak to hold in the gases, sun heated gases and they escaped Earth’s gravity
- Volcanoes created a new atmosphere (outgassing)
What is the evidence that there was a lack of free oxygen in early Earth?
- Pyrite
- Cyanobacteria
- Stromatolites
- Banded iron formations
- Redbeds
What effects would an oxygen-rich atmosphere have on the Earth?
- Gigantism in certain species (insects)
- High species diversity
- Low production of new species
- Huge fires- oxygen is highly flammable
What effects would a low oxygen content atmosphere have on the Earth?
- Mass extinctions
- Low species diversity
- More appearances of new species (nature’s way to find a new way to survive)
- Dinosaurs
What is the source of each major gas in the current atmosphere?
- Argon: radioactive decay
- Nitrogen, carbon dioxide water vapor, argon: volcanoes
- Oxygen: separated from carbon dioxide by photosynthesis
Why did dinosaurs thrive in a low oxygen content atmosphere?
- Developed an efficient respiratory system involving air sacs to move air through the lungs (like a bellows)
- Oxygen contents rose- more types of dinos, larger dinos
Why did birds thrive in a low oxygen content atmosphere?
- Evolved from dinosaurs
- Same efficient breathing system as dinosaurs
- Enabled birds to fly high / far and do hard physical work in thin air
Adiabatic cooling
- Air cools as it thins
- The temperature of an air mass decreases as the air mass rises and expands
- Air density is lower at higher altitudes- air mass expands/less particles/movement to meet equilibrium
- Uses energy to expand- cools down
Auroras
- Sun emits solar wind- charged particles (protons+electrons)
- Emitted by surface of sun at speed 1-2 million mph
- Drawn to Earth’s magnetic fields (poles)
- Slam into atmosphere, transfer energy to atmospheric atoms
- Atoms emit visible light in order to return to low energy state
Banded iron formation
- Started 2.5-1.7 billion years ago
- Oxygen combined with dissolved iron in Earth’s oceans to form insoluble iron oxides- formed a thin layer on the ocean floor
- Oxygen mixed with iron in the oceans, rusted iron collected on the seafloor
Chlorofluorocarbon
- Used in refrigerants, aerosol spray, and foam packaging
- Destroy the ozone layer
Photosynthesis
The process of turning carbon dioxide and water into glucose and oxygen with the help of solar energy
Redbed
- Rocks that rust due to oxygenated iron presence (iron oxide) in the second half of Earth’s history
- Oxidized iron in cement
Stromatolite
- Layered bulb-like structures produced by colonies of algae and the sediment that they trap
- Single celled organisms that produced oxygen (slowly)
- Most advanced lifeform for 3 billion years
- Eaten later on by new species
Greenhouse gas
- Traps heat in the atmosphere
- Carbon dioxide
- Methane
Cyanobacteria
Tiny organisms that produced oxygen by photosynthesis 3.5 billion years ago (blue-green algae)
Fossil fuels
- Remains of plants of animals
- Come in the form of oil, coal, or natural gas
- Energy from the sun
- Result of the decomposition of dead plant and animal matter buried deep in the Earth’s crust
- Pumped from underground and burned to create energy
Where is the most common place to find stromatolites today?
Shark Bay in Australia
Timeline of oxygen on Earth
1) 2.7- 3.5 bya: cyanobacteria in oceans made free oxygen by photosynthesis
2) Stromatolites formed from Cyanobacteria
3) 2.5-1.7 bya: banded iron formations, continued until there was no more iron in the oceans to rust. Oxygen had nowhere to go but into the atmosphere
4) 2 bya: red beds formed when oxygen was released into the atmosphere
How and why has the carbon dioxide content level in the atmosphere been changing recently?
-Use of fossil fuels
-Releases CO2 into atmosphere
-
What is good vs bad ozone?
GOOD: occurs naturally, protects us from ultraviolet radiation (causes sunburn, skin cancer, eye cataracts)
BAD: product of air pollution, damages respiratory system
Pyrite
- Iron+sulfate (fools gold)
- Rusts when exposed to oxygen to form oxidized pyrite
- Shiny before rusting
- Pyrite in sediments still shiny- no oxygen in Early Earth to oxidize it
Limestone
When carbon dioxide gets deposited on the ocean floor, it forms as part of limestone (does not dissolve)
Why would oxygen contents increase and decrease?
- Rotting vegetation removes oxygen
- Swampy areas + densely vegetated regions- plant matter may not decay before rapidly buried by more plant matter- allows oxygen levels to rise
- Mountain building- O2 content falls
What happens during periods of mountain building? What is the result?
- Deep carbon rich layers may be brought to the surface and eroded
- Carbon + oxygen- carbon dioxide
- Result: oxygen content falls, carbon dioxide content rises
Adiabatic lapse rate
How rapidly air cools as it rises
1 degree C / 100 meters
When did dinosaurs go extinct?
65 million years ago
Asteroid impact- ash blocked sunlight for a long time
Where does the most dramatic ozone depletion occur every year and why?
- Antarctica
- Specific chemical reactions that deplete the ozone in the stratosphere over Antarctica require cold temps only found in this region
