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