Lecture 2 Flashcards
What is the surface pressure of the earth?
1 (atm)
What are the 2 main constituents of the earth?
N2 (78%) and O2 (21%)
When did the earth’s first atmosphere exist?
existed 4.6-4.0 bill years ago
Was there oceans in the earths first atmosphere?
No
What eroded the earths first atmosphere?
Solar wind and cosmic rays
What contributed to the break down of NH3 and CH4, freeing N and H?
Surface heat
In which stage of the atmosphere did the earth cool and develop a solid crust?
Earths ‘second’ atmosphere
What activity contributed to the formation of magnetic field capable of deflecting solar wind and cosmic rays?
Convective Magma activity
What type of activity formed in the earths ‘2nd’ atmosphere that was linked to outgassing and contributed to the high atmospheric temperatures (>100 degrees Celsius) ?
Volcanic activity
Also tectonic activity, due to frictional heating from meteorite impacts and strong GH effect
When did oceans form and what caused the formation? (3 causes)
3.8-3.9 bil years ago
- Temperature cooled below 100 –> condensation of water vapour and precipitation became possible
- Expansion of oceans acted as sink for atmospheric CO2
- Anaerobia bacteria began to develop in deep ocean near volcanic hydrothermal vents
What allowed the ozone layer to form 1 billion years ago?
The saturation of the ocean with oxygen, + subsequently O2 could accumulate in the atmosphere
What appeared 3.8-3.5 bil years ago as the 1st O2 producing organisms? (Photosynthesis)
Prokaryote Cyanobacteria (‘blue-green algae’)
How deep did the prokaryote Cyanobacteria live in the ocean to be protected from harmful radiation but still within the range of sunlight?
75m
How many years ago did present day atmosphere occur?
400 mil years ago
What are 2 essential requirements for plant life on land?
Ozone layer and protection from harmful solar radiation
What does CO2 + H2O + sunlight lead to…
Organic compounds + oxygen (O2)
Atmospheric pressure is the consequence of…
The atmospheres own weight
What percentage of atmospheric mass is below 10km?
90%
What satellite orbits the Earth at the same rate as the earth rotates, thus remaining stationary on a single line of longitude?
Geosynchronous (GEO)
Name the four atmospheres in order of lowest (nearest to surface) to highest?
Troposphere, stratosphere, mesosphere, thermosphere
When an air parcel rises, what happens?
It expands and cools
When air descends, what happens?
It compresses and warms
What are the 3 basic laws of thermodynamics?
- Energy can be transformed but not destroyed
- Heat can never pass spontaneously from a colder to a hotter body; a temp change can never occur spontaneously in a body at uniform temperature
- Systems tend towards equilibrium, a random distribution of energy over time
What are the two layers of the vertical structure? (Functionality)
Upper - ionosphere (>50km) - ions created by solar UV radiation
Lower - ozone layer (ozonosphere) (approx 20-50km)
What’s the homosphere (extends from sea level to mesopause) composed of?
Mixing ratio of oxygen to nitrogen, as well as long lived trace gases
What’s happens in the heterosphere (above 80km)?
Altitude molecular separation - due to gravitation with the heaviest molecules at the bottom and the lightest at the top
What is the air made up of?
78% nitrogen (N2)
21% oxygen (O2)
Remaining 1% = argon + GHGs
Abundance of water vapour = depends on physical properties (temp) and is highly variable
What is a particulate?
Suspended solids/liquid droplets other than H2O droplets/ice crystals
What are aerosols?
Mixture of air with suspended particulates
What are the effects of particulates in the atmosphere?
Reduction in visibility (haze) - scatters incoming light and absorbs outgoing thermal radiation
What is the mean surface temperature of the earth?
288 (k), equivalent to 15 degrees Celsius
