Lecture 2: Atmosphere Flashcards
What is an atmosphere? My notes
we know we have an atmosphere as we have a blue sky- few indications
We don’t have extreme atmosphere from equator- atmosphere redistribute energy- ocean also does too
moon has big diff b/w equator and poles goldilocks planet
Venus has 90 atmospheres - much thicker- Venus must of had ocean and liquid water but as sun grew in intensity- oceans boil- water enter into venus atmosphere- hotter than mercury cause go green houses effects
Mars much slimmer atmosphere
Earth’s first atmosphere- my notes
light gasses- i.e ammonia
Earth didn’t have magnetic field- mostly molten- no longer protected by solar winds- blew atmosphere away
second atmosphere- when earth surface became crust- convection currents in earth’s mantle- therefore magnetic field- protection from solar flares
no oxygen- its a function life- sign of life
very hot atmospheric temp
water couldn’t form- no life could evolve either
Formations of oceans- my notes
water condense in liquid water- accumulate- when the earth became cooler - life evolved in oceans- anaerobic bacteria- deep in oceans- didn’t need oxygen
The oxygen catastrophe- my notes
shallow waters- no ozone layer- no protection from uv rays
oceans became saturated- oxygen went towards the atmosphere
Deadly saturation of ocean- mass extinction of aerobic bacteria
Earth’s third atmosphere- my notes
More complex life systems= oxygen
1 billion years ago only 1% of oxygen
ozone layer- key for development of human life and more complex life systems
Understanding our atmosphere - my notes
WMO GOS- look at slide
-Surface observations
Remote sensing- geostationary orbit- orbit the earth in 24 hours- over the equator- only looks at that particular area- global network of satellites - gives global coverage
Polar orbiting satellites- orbit earth north and south- orbit the earth 90 mins
our atmosphere- my notes
earth’s gravity keeps molecules close to the earth- thats why we have an atmosphere
Extra notes (my notes)
altitudes: climbing 40% less air- less oxygen at 4000km
- 90% of our atmosphere is below 10km
- atmosphere vertical profile: temp- warmth from earths surfaces passes on to the atmosphere
- interaction of uv light- absorption of ozone layer- heats the stratosphere from above
- thermodynamics- warming of the bubble of air- like a balloon - expand
- sinking air- air doing work on air mass- push against something- going to get hot
Composition of the atmosphere air: my notes
- Nitrogen, oxygen mostly
- Carbon dioxided- is a passing gass
What is an atmosphere?
Obviously we need air to breathe
• No lakes or oceans without atmosphere
• Extreme temperature ranges without atmosphere
• No sound without air
• No protection from meteorites, however small they might be
• No protection from UV radiation
• Air is a tasteless, odourless, mostly invisible homogeneous mixture of gases.
Atmospheres of other planets: Venus
mean surface temp (k): 750 ( 500 c)
Surface pressure (atm): 90
Gravity acceleration (m s-2): 8.84
Main constituents: CO2 96% N2 4%
Sulphuric acid clouds complete cover
Atmospheres of other planets: Earth
mean surface temp (k): 288 (15 c)
Surface pressure (atm): 1
Gravity acceleration (m s-2): 9.81
Main constituents: N2 78% O2 21%
50% cover h20 clouds
Atmospheres of other planets: Mars
mean surface temp (k): 218 (55 c)
Surface pressure: 0.006
Gravity acceleration (m s-2) 3.76
Main constituents: CO2 95% N2 3% some very thin h20 clouds
Earths first atmosphere:
Topic of much debate (present knowledge is associated with large uncertainties)
• Existed 4.6–4.0 billion years ago
• Composition is likely to have included H2, He, NH3, and CH4
• No oceans on Earth!
• Atmosphere was probably eroded by solar wind and cosmic rays
• Surface heat contributed to breakdown of NH3 and CH4, freeing N and H
