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