Chapter 10: Planetary Atmospheres Flashcards
What is an atomosphere?
A layer of gas that surrounds a world.
What is the greenhouse effect?
A process in which the infared light that is emmited by a planet is absorbed by green house gasses. This increases the overall temperature of the atmosphere.
What are greenhouse gases?
Gasses that can absorb infared light.
Without the greenhouse effect, what would a planet’s average surface tempurature depend on?
The planet’s distance from the sun.
The planet’s overall reflectivity.
What are the four basic layers of Earth’s atmospheric structure.
Troposphere, Stratosphere, Thermosphere, and Exosphere
What heats the troposphere?
Infrared light emmited by the ground is absorbed by greenhouse gases. This heats the troposphere.
Why does the troposphere have storms?
The heat from the ground causes convection, combined with the relatively high density of air in the troposphere.
What heats the stratosphere?
Ultraviolet light which is absorbed by ozone.
What effect does the greenhouse effect have on the stratoshphere?
Very little effect as the air density is too low.
What is a requirement for a planet to have a stratosphere?
It must contain molecules that are particularly good at absorbing ultraviolet photons such as ozone.
Why does tempurature increase with altitude in the stratosphere?
Most of the ultraviolet absorbtion and heating occurs at moderately high altitudes in the stratosphere. This prevents convection.
Why is there no weather in the stratosphere?
Because convection is impossible in the lower stratosphere as air gets hotter as altitude increases.
What heats the thermosphere?
X-rays from the sun.
Why doesn’t the exosphere absorb the x-rays?
The density of the exosphere is too low.
What effect is responsible for the ionoshpere?
The ionization of atoms in the thermosphere by x-rays.
What is the exosphere?
An extremely low density gas that forms the boundary between the atmosphere and space.
What is the magnetosphere?
The protective magnetic field that surrounds the earth
What is the function of the magnetosphere?
It deflects the majority of solar wind particles around it
What happens to the solar wind particles that get through?
They move allong the magnetic field lines and collect in charged particle belts
What is weather?
The ever-varying combination of winds, clouds, temperature, and pressure.
What is climate?
The average weather over many years.
What would happen to atmospheric heating if earth did not rotate?
There would form two circulation cells. One over each hemisphere of the earth.
What is the coriolis effect?
The effect due to rotation that causes air or objects on rotating surfaces to deviate from straigh line tragectories.
What are the four major factors that contribute to long term climate change?
Solar Brightening
Changes in Axis Tilt
Changes in Reflectivity
Changes in Greenhouse Gas Abundance
What do models say about the brightness of the sun over time.
The models suggest that the sun has increased in brightness over time.
How do changes in a planet’s axis tilt affect its climate?
Changes in axis tilt make seasons either more or less extreme.
What does a greater axis tilt result in.
More extreme seasons which means warmer summers and colder winters. This prevents ice from building up reducing a planet’s overall reflectivity.
What are the three basic ways terrestrial atmospheres gain gas?
Outgassing
Vaporization
Surface Ejection
What is outgassing?
The primary source of gases for Venus, Earth, and Mars. Occurs when gas trapped in the earth during accretion is released during a volcanic eruption.
What is surface ejection?
Occurs when tiny impacts knock individual atoms or molecules free. This is the explanation for the small amounts of gas that suround the moon and mercury.
What are the four main ways terrestrial atmospheres lose gas?
Condensation
Chemical Reactions
Solar Wind Stripping
Thermal Escape
What is solar wind stripping?
Occurs when solar wind strips way gas particles into space.
What is Thermal escape?
Occurs when an atom or molecule in a planet’s exosphere achieves escape velocity.
Do the moon an mercury have atmospheres?
Only low density exospheres.
What is the Runaway Greenhouse Effect?
The process in which the green house effect increases globa average temperatures, which in turn increases the intensity of the greenhouse effect. This is known as a positive feedback loop.
What are carbonate rocks?
Rocks rich in carbon and oxygen.
Why is the temperature of venus so extreme?
The huge amount of carbon dioxide in Venus’s atmosphere results in an intense green house gas.
Why does venus experiene little wind?
Slow rotation means a very weak coriolis effect.
