Intro pt. 1 Flashcards
*
4 Major ‘spheres’
- lithosphere
- hydrosphere
- atmosphere
- biosphere
envelope of gas that surrounds the Earth
atmosphere
- boundary between ____ and space, not sharp
- but ________ km of Earth’s surface
- the bulk (99% by mass), in the lower _____ km
- Atmosphere
- 80, 000 km
- 50 km
The atmosphere:
* acts as a ______, removing DNA-destroying high energy UV-radiation;
- traps infrared radiation, transforms it into ____________ → warming the surface
- forms a ____ through which life-sustaining energy and matter move
- filter
- Thermal motion
- conduit
________, prior to life, formed from
outgassing from interior of the planet
- probably dominated by H2. He, small
concentrations of NH3, H2O, CO2 and N2 - … more from volcanic eruptions, … also S
primitive atmosphere
Irradiation of the _______ with UV light from the sun would have facilitated the reactions:
H2O + hv (λ<240 nm) → H + OH
CO2 + hv (λ<240 nm) → CO + O
(hv = photon of light; λ = wavelength)
The products of these reactions are _______.
prebiotic atmosphere
free radicals
____ are chemical species containing unpaired electrons and are generally highly reactive.
Free radicals
The atmosphere underwent a dramatic change with the evolution of _________.
photosynthetic organisms
________ convert CO2 and H2O to carbohydrate and oxygen
Probably, the initial low concentration of O2 in the atmosphere made formation of life possible
photosynthetic organisms
The ____that developed in oxygen-poor atmosphere (i.e., anaerobes) are forced to live in secluded environment (sediments, intestinal canals).
primitive organisms
- Although, photosynthesis forms carbohydrates (plant biomass), not all these plant matter are recycled back to the atmosphere through ______ (oxidative decay, forming CO2).
- Some of these carbohydrates are effectively permanently removed, e..g. buried in the _____, forming part of the soil and in time fossil matter.
- respiration
- sediments
- complex mixture of gases and suspended particles
Present Atmosphere
Present atmosphere dominated by two gases:
* _____ and _______, which together account for 99% of the volume of dry air
* _____ + other gases of varying concentrations, normally considered as pollutants: 1%
- N2 (78 mol%) and O2 (21%)
- Argon
The major components of dry air in the troposphere (lower 15 km)
* Nitrogen, N2
* Oxygen, O2
* Argon, Ar
* Carbon dioxide, CO2
Mol Percent? Mass Percent?
- Nitrogen, N2 - 78.09, 75.51
- Oxygen, O2 - 20.95, 23.15
- Argon, Ar - 0.93, 1.23
- Carbon dioxide, CO2 - 0.03, 0.05
______ also contains trace gases, particulates and water.
Dry air
Origin & Composition:
Several trace gases: CO, NOx, CFCs, SOx and CH4
* Atmospheric composition: ______
Relatively stable
____(anthropogenic activities) is
removing the steady-state condition
* CH4, rising by about 1% annually?!
Human intervention
_________
* very low density, low pressure
(< 10-5 atm)
* ______, formed when
high-energy short-wave solar
radiation (λ«_space;200 nm) is
absorbed.
Thermosphere
* Atoms and ions
Thermosphere
________; tend to recombine, release energy
* Energy →motion of molecules,
atoms or ions→warming of
thermosphere
Products are reactive
The temperature of the thermosphere
decreases with decreasing altitude,
until the ______ is reached (about
90 km).
mesopause
Thermosphere
Due to: the particles in the upper
thermosphere absorb the _______, which is responsible for the warming effect in the thermosphere.
short-wave radiation
Below the mesopause (in the _________),the molecular species facilitates warming by the absorption of solar radiation (200 λ 300 nm).
mesosphere and stratosphere
In _______:
At decreasing altitude, the population
(concentration) of the molecular species increases. → increasing T at decreasing altitude
mesosphere
In _______:
But as altitude decreases, the amount of the radiation (200 λ 300 nm) decreases as it has been removed at higher altitudes. → decreasing T at decreasing altitude
Stratosphere
