Intro pt. 1 Flashcards
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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
there is a maximum temperature in the mesosphere-stratosphere region. →
_________.
stratopause
Solar radiation energy→absorbed by
molecules→thermal motion→chemical reaction
* Ozone production
Where?
Stratosphere
- UV light dissociates oxygen molecules to O atoms
- O2 atoms combine with another oxygen molecule (exothermic)
Formation of ozone
The Stratosphere & Ozone:
Thus, there is a maximum O3
concentration at a certain
height.
(__ km at the poles, ___ km at the
equator)
15 km
30 km
not a major constituent of any part of the atmosphere.
found only at trace levels at all altitudes.
Ozone
the part of the stratosphere where ozone has its maximum concentration (8-10 ppm).
“Ozone layer”
If all the ozone within the atmosphere were concentrated at sea level,
it would be only about _____ thick.
3 mm
The ozone layer protects the Earth from much of the short-waved
_____.
radiation
The radiation absorbed by the gases leads to _________by:
absorption of solar UVC (< 280 nm) radiation by O2
absorption by UVB (280 - 315 nm) and UVC radiation by O3
Absorption of IR radiation from Earth by O3
localized heating
creates an inversion that stabilizes against vertical air movement.
localized heating
Troposphere
Contains about ____ of the mass of
the atmosphere
* _______ reactions among various
molecular species
* Key to many chemical processes:
____ and _____ radicals
- 90%
- Complex
- OH and NO3
Troposphere
Nitrogen, oxygen and argon are not greenhouse gases!
Greenhouse gases: (4)
(methane)
H2O, CO2, CH4
Troposphere
The concentration of these
greenhouse gases (which cause
warming) _______ as altitude
decreases → temperature ______ as altitude decreases
increases
limits the flux of matter
from the troposphere to the
stratosphere.
Tropopause
weather occurs at the ______
troposphere
The higher layer: Thermosphere
* Temperature ____with increasing altitude
* UV radiation is absorbed by ______ molecules forming ions and electrons
- increases
- oxygen
- Over the thermosphere, above 700 km:_________
- An increasing number of ionized particles form the _________.
- Atmosphere extends to a height of _____ km
Exosphere
Van Allen Belts
80,000 km
The composition of the atmosphere is mainly constant, … result of _______ including
* Emissions
* Possible transformations
* Reactions with other compounds
* Eventual removal by deposition
which is ___ of substances in the atmosphere
global cycles
lifetime
```
Reactive compounds → short lifetime
High emission, slow deposition, inert → long residence time, high concentration
Global Circulations
Solid materials, … aerosols (so
small)…important as _______ in formation of clouds
condensation nuclei
__________
* Water vapor, fluid (droplets, rain), solid (ice, snow)
* Part of the hydrological cycle
* Only ______ of the global water
Atmospheric Water
0.001%
The dominant transport of water between the oceans and the land masses takes place via
the ______
atmosphere
- concentration strongly varying (global average 4 vol. %)
- Concentration: often as relative humidity (actual vapor pressure/vapor pressure of water at saturation at the given temperature)
Water Vapor
