Chapter 11 Flashcards
Define an atmosphere
A fluid/gas surrounding the solid surface/ interior of a planetary body
Compare the atmosphere of the Jovian planets to those of the Terrestrial planets
Jovian planets have large atmospheres which make up most of the planet’s mass. The atmospheres around terrestrial planets are thin, dense, and do not contribute a significant amount to the mass of the planet
How does the atmosphere affect the surface of a planet?
The movement of air as it modifies the landscape to produce surface features
What does the atmosphere tell us about the evolution of a planet?
The composition of an atmosphere tells us about what is going on at the surface and in the planets core
How do atmospheres help us in studying comparative planetology
The atmosphere can provide records of ancient climate elsewhere (which helps to constrain how Earth has evolved)
What are 4 different types of atmospheres?
Gas giants, Thick, Vapour pressure, Tenuous
Why do pressure and density decrease with altitude?
Because of the weight of overlying layers is less (therefore less gravity)
At what distance does matter have to be to be coincided part of Earth’s atmosphere?
The Matter must be < 100km from the surface of the Earth
Name 5 effects of an atmosphere
- Creates pressure (determines if liquid water can exist on surface) 2. Absorbs and scatters blue light 3. creates wind, weather, and climate 4. interacts with solar wind to create aurora 5. can make the planet’s surface warmer through the “greenhouse effect”
At formation, what were all terrestrial planet’s atmosphere’s composed of?
Light gases similar to the primordial mixture of gases found in the Sun and Jupiter
What are the three processes that produce the secondary atmospheres we see on Venus, Earth, and Mars today?
Loss processes (the escape of atoms into space), replacement by geological outgassing (volcanoes), and biological processing
Why are hot. small bodies less likely to have an atmosphere?
Because of thermal escape (i gas may have a thermal kinetic energy greater than a planets escape speed)
Describe Venus’ atmosphere
Hot, thick and mostly composed of carbon dioxide
Describe Mar’s atmosphere
Thin, cold and mostly made of carbon dioxide
Describe Earth’s atmosphere
Moderate and mostly composed of nitrogen and oxygen
Describe the atmosphere’s of both the Moon and Mercury
Non-existent
Describe 4 processes important in determining the heating of an atmosphere
Infrared photons are absorbed causing molecules to vibrate; some visible light photons are scattered; UV photons can dissociate molecules; X-rays can dissociate molecules and ionize gases
What is the Greenhouse effect?
Carbon dioxide (and to a lesser extent water) molecules are very effective at trapping IR radiation (heat). Will act as a blanket for the planet and raise the temperature
Constant temperature is achieved when energy in is equal to what?
Heat loss
What does the Greenhouse effect help Earth avoid?
A perpetual ice age
On which planet does the Greenhouse effect cause the hottest planetary surface in the SS?
Venus
What are the 3 stage of the CO2 cycle on Earth?
The atmosphere dissolves into water and ends up in the ocean, reacts chemically to form a variety of carbonate rocks, will be released back into the atmosphere when plate tectonics are heated and volcanic activity occurs
What is the Faint Sun Paradox?
The early sun is expected to be 25-30% fainter than today, so liquid water would not have been present under current atmospheric conditions
UV radiation could combine with existing methane to form solid hydrocarbons in the upper atmosphere, which would shield ammonia long enough for it to produce greenhouse warming adequate for liquid water. To what problem may this be a possible solution?
The Faint Sun Paradox
What is the theory of a “snowball Earth”
There is (controversial) evidence that the Earth was completely covered in glacier about 600-700 million years ago
What evidence do we have that there are high-speed winds on the surface of Venus?
Stable circulation pattern
Why is it that Mars does not release as much carbon dioxide as Earth or Venus?
Mars seems to have much less geological activity than Earth and Venus, therefore, less release
Why is Mar’s loss of atmosphere much more severe than Earth or Venus?
Because of its lower gravity
Where does the energy driving Earth’s atmosphere come from?
From the Sun
What does the final temperature for Earth (and its atmosphere) depend on?
Depends on the equilibrium between heat input and heat loss
What are the two processes in which heat is redistributed in Earth’s atmosphere?
Radiation and convection
Why is the convection of Earth’s atmosphere important?
It is crucial in producing weather on Earth
What is the adiabatic assumption?
When a parcel of warm air rises, it responds to the change in pressure almost instantly, but takes longer to come to the same temperature of the air around it
Because of the adiabatic assumption, the warm air will continue to rise as it is not in equilibrium with its surroundings. What stops it from just rising to the “top”?
Because the pressure will continue to decrease, the parcel will have to continue to expand, this expansion takes work (which comes from the thermal energy) and therefore cools
At what rate must an atmosphere’s temperature change to be vertically stable?
At the adiabatic lapse rate
In what region of Earth’s atmosphere does the weather take place?
The troposphere
What is the thin layer between the troposphere and stratosphere?
The tropopause
What are the 2 layers above the stratosphere?
The mesosphere and the ionoshpere (or thermosphere)
Which layer is responsible for absorbing the most energetic photons from the Sun?
The ionosphere
What is the coriolis effect?
The more rapid the rotation of a planet the more large-scale eddies (belts of wind and belts of clam) are created
What direction to weather pattern in the north and south hemisphere deflect to?
North = right, south = left
What energy drives the winds?
Driven by solar heating
What are the 3 major convection zones for wind flows on Earth?
Polar Easterlies,Westerlies, and Trade Winds
What is the only system that can produce large amounts of oxygen in a terrestrial atmosphere?
Biological systems
What is the function of the Ozone layer?
It absorbs UV radiation from the sun
In what layer is the Ozone located?
In the stratosphere
What compound can destroy the ozone layer chemically?
Chloroflorocarbons (CFCs)
What is the first of 2 theories for climate change?
The “habitable zone” in the SS is very narrow and any small change in temperature can send a planet toward runaway greenhouse effect or runaway icebox
What is the second of two theories for climate change?
The biosphere itself is self-stabilizing, and a large range of conditions can still be habitable
The Earth’s surface being heated by the Sun’s radiation, absorbing and re-radiating mostly as heat, and being trapped by the atmosphere, is what effect?
The Greenhouse effect
What is an enhanced greenhouse effect?
When too much carbon dioxide, water and methane build up and trap too much heat
Is the global warming we are experiencing now due to human activity or natural variability?
It is consistent with the human production of greenhouse gases
What is the main component of Venus’ atmosphere?
Carbon dioxide
What are the two methods of spectroscopy used to determine atmospheric composition of Venus?
Ground based telescope and robotic balloons and landers
How are the sulfuric acid clouds on Venus formed?
The S and SO2 (from volcanic outgassing) combines with small amounts of water to form these clouds
What are 3 reasons that Mars’ atmosphere is so thin?
- weak gravity = escape of gases, 2. Low temperatures, 3. Gas incorporation into rocks during an early Martian ocean
What are 3 theories for thin Martian atmosphere?
- Dissociation and thermal escape, 2. Loss by large early impact, 3. Failed carbonate cycle
Why could the heavy bombardment have striped Mars of its atmosphere but not Venus or Earth?
Because of Mars’ low atmosphere
Why is Mars self limiting when it comes to water?
Because the atmospheric pressure is just below the point where water could exist and the atmosphere is not thick enough to counteract this
How do we know that there was liquid water on Mars in the past?
The current atmosphere doesn’t allow for water, but we see water-related surface features
How to do we know that the Martian atmosphere was more dense in the past?
There is an under balance of medium-sized craters, which suggests high erosion rates
To what planetary atmosphere does Mars’ atmospheric structure compare?
Venus also has no cold traps
What gives the Martian atmosphere a reddish hue?
Dust in the lower layers
What does the large variation in temperature and pressure across Mars result in?
Strong winds systems which create dust devils
What is the primary component of Titan’s atmosphere?
99% nitrogen
Why does Titan have a thick layer of smog in its atmosphere?
Because of sunlight interacting with hydrocarbons (same way as on Earth)
What are 4 results of the Huygens Probe on Titan?
Liquid methane on surface, “rocks” constitute dirty ice, surface temperature 94K and geologically active
What are the 3 reasons that Titan was (the only moon) able to form an atmosphere?
- temperatures were sufficiently cold that an primordial atmosphere was able to form, 2. High enough mass to retain gases, 3. surface temperatures warm enough to prevent some volatiles from freezing out
What are the 5 factors that affect the composition of terrestrial secondary atmospheres?
- Distance from the Sun, 2. Mass and radius of the planet, 3. Chemical reactions, 4. Geological activity, 5. Living organisms
