Announcements• The last Dark Sky Observing Night is tonight. Starts at 7:30pm at the APSU Observatory on “The Farm”. Try to arrive a little early so your lights don’t interfere with the observing in progress.
• Since there is a high chance tonight will be cancelled, we will try again tomorrow night (Tuesday). There is also a Dark Sky Alternative posted in www.apsu.edu/astronomy/dark-sky-observing-night
The Greenhouse Effect Lecture-Tutorial
The greenhouse gasses are mostly CO2 and H2O but CH4 and a few others also contribute
iClicker Question
The main reason Earth’s average temperature is not below 0°C is because
a)volcanoes heat the atmosphere.b)solar radiation alone is enough.c) the greenhouse effect warms the
ground above what it would otherwise be.
d)continental drift and tectonics adds heat to the atmosphere.
Another iClicker Question
The greenhouse effect is caused mostly by
a)the aurora borealis.b)pesticides.c) depletion of the ozone layer by
manmade CFC’s.d)carbon dioxide and water vapor in
the atmosphere
One More iClicker Question
The Earth’s surface absorbs energy from sunlight and then radiates the same amount of energy back into space. The best proof for this fact is that the average annual surface temperature on Earth is
a)warming rapidly.b)not changing much.c) cooling rapidly.d)fluctuating wildly.
Earth’s Atmosphere is layered
like an onion
The layers are due to how the temperature changes with altitude. Mars and Venus don’t show the same kind of layering.
The way temperature changes is due to energy
transport
In the troposphere convection is driven by heat from the ground
In the stratosphere and thermosphere energy is absorbed directly from the sun
Just as in the interior of the planets, convection is
important to atmospheres
Rotation and the Coriolis effect are also important
Magnetic fields are also very important to atmospheres
Earth’s relatively strong magnetic field protects our atmosphere from erosion by the solar wind
The weak or non-existent magnetic fields of Venus and Mars lead to strong erosion
by the solar winds
iClicker Question
ClassAction websiteTerrestrial Planets module
Magnetic Fields andAtmospheres
Another iClicker Question
If its mass was closer to that of Earth and Venus, Mars might
a) still have an active interior.b) have a thick atmosphere.c) have abundant liquid water
and larger ice caps.d) have a strong magnetic field.e) All of the above.
Is mankind changing Earth’s atmosphere?
Man?
Each spring in Antarctica a hole develops in the ozone
layer
Ozone depletion is caused by CFC’s
CFC’s are Chlorofluorocarbon molecules which are man made compounds. They do not occur naturally
The solution: stop using CFC’s
The 1987 Montreal Treaty gradually reduces the production and consumption of CFC’s worldwide
Is the Ozone Hole getting worse or better?
Our actions have led to an increase in the level of a number of greenhouse
gasesUnfortunately, we can’t stop producing these gases as easily as we stopped producing CFC’s
Deforestation has a major impact Earth’s atmosphere
Deforestation removes the trees that remove CO2
The cut trees are usually burned which adds more CO2 to the atmosphere
There is a direct relationship between the level of CO2 and
the global average temperature
One model of where it will get hot
in the future
based on increases
in CO2 levels
All models predict that it will get warmer
We are performing an experiment on our atmosphere.
What the outcome will be we don’t yet know
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