Question: Describe a greenhouse. What is it? What is it like inside and why?

Answer: … … …

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The Greenhouse Effect

• Approximately half the light that comes from the sun doesn’t make it to the surface of the earth.

• X-rays, a lot of incoming IR and UV are absorbed before they reach the surface.

Some of the light that reaches the earth’s surface is changed to heat (IR) and is trapped by “Greenhouse Gases” in the atmosphere.

How does a Greenhouse work?

• What’s different about the two waves shown in the picture?– Different wavelengths

• Visible light (from the sun) – Has shorter wavelengths– Can pass through glass/

greenhouse gases.

• Infrared light (heat) – Has longer wavelengths.– Cannot pass through glass/

greenhouse gases and is reflected back.

• Draw this picture noting the difference in wavelength

The Greenhouse Effect on Earth

• The greenhouse gases act just like the glass in a greenhouse.

The Greenhouse Effect is Good for Life on Earth

• Without the Greenhouse Effect– Reflected IR radiation (heat) would be lost

to space– Earth’s temperature could vary from about

-380 to 250 oF during a day (like on the moon)

Greenhouse Gases

– Don’t make up a very large percentage of the atmosphere, but have a significant warming effect.

Greenhouse Gases

• CO2 (carbon dioxide)

• CH4 (methane)

• NOx (Nitrous oxides)

• CFC’s (Chloroflourocarbons)

• H2O (Water Vapor)

So What’s The Big Deal??• The human-caused enhancement of the greenhouse effect is

called global warming and it’s bad because it’s associated with climate destabilization

Runaway Greenhouse Effect

• Atmosphere of Venus is mostly CO2

• Temperatures can reach A. 300oF

B. 1000oF

C. 500oF

D. 860oF

Artist’s idea of what Venus’ surface might look like

Venus’ Atmosphere

CO2 Concentration on Earth

• What is the trend of CO2 Concentration in earth’s atmosphere?

Global Warming/Climate ChangeEven small increases in the amounts of CO2 in the atmosphere can increase our temperature AND change the climate!

Where Does CO2 Come From?

• Combustion of Fossil Fuels in– Power Plants– Cars– Factories

Where Does CH4 (methane) Come From?

– Naturally occurring in swamps

– Released as by-product of rice and cattle farming.

Where Does NOx Come From?• Burning of fossil fuels like

gasoline, coal, and natural gas

• breakdown of fertilizers in soil

CFC’s (Chlorofluorocarbons)• Also degrade ozone layer in

addition to being a greenhouse gas

• Come from– Spray cans (banned from USA

spray cans in 1995)– Coolants in refrigeration systems

and air conditioners – Solvents to clean electronic

components– Blowing agents in the production

of plastic foams like styrofoam

Where Does H2O (Water Vapor) Come From?

• It’s all around us• most abundant

greenhouse gas• not directly

influenced by human activity (So we don’t worry too much about it!)

Which greenhouse gas is most responsible for global

warming?

A. MethaneB. Water VaporC. CFCsD. Carbon Dioxide

Effects of Global Warming• Which of the following are probable results of global

warming due to excessive greenhouse gases?A. thinning of polar ice capsB. floods C. Droughts/ water shortagesD. All of the above In addition to:

• rising sea levels (threatening millions of people) • changing precipitation patterns• heat waves• disruptions of forests and agriculture

• Yet we continue this uncontrolled, global experiment!

What Can We Do About It?

• Reduce Greenhouse Gases by:

• Use alternative energy that doesn’t emit CO2

• Conserve energy by turning off lights, riding bicycles, etc.

• Reduce, Reuse & Recycle

• And the list goes on!

What Can We Do About It?

GtC = Gigatons of Carbon emissions = 109 = 1 billion

Lab: The Greenhouse EffectLab: The Greenhouse EffectLab: The Greenhouse EffectLab: The Greenhouse Effect

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2. Identify which of the following gases is most abundant in Earth’s atmosphere today.

a. argon c. oxygenb. nitrogen d. carbon dioxide

2. Nitrogen is most abundant in Earth’s atmosphere today.

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3. Compare Earth’s early atmosphere with its present atmosphere.3. Earth’s early atmosphere was composed of many gases that would be poisonous to us today. As life forms evolved and began to photosynthesize, oxygen was produced. Once animals adapted to breathing oxygen, they began to give off carbon dioxide, balancing the production of oxygen.

4. Arrange the steps of the oxygen-carbon dioxide cycle in the correct order:

a. Animals breathe oxygenb. Plants produce oxygenc. Plants use carbon dioxided. Animals exhale carbon dioxide

4. The correct order is b, a, d, c.b. Plants produce oxygena. Animals breathe oxygend. Animals exhale carbon dioxidec. Plants use carbon dioxide

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5. Explain why the following statement is incorrect: global warming could cause oceans to rise, so the greenhouse effect must be eliminated completely. 5. If we were to eliminate the greenhouse effect completely, the world’s climate would become too cold for humans to survive.

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p. 605 CYU 2-7 p. 605 CYU 2-7 p. 605 CYU 2-7 p. 605 CYU 2-7 6. Predict how much colder it is at the top of Mount Everest, which is almost 9km above sea level, than it is at the Indian coastline. Consider only the difference in altitude. (Hint: the temperature in the troposphere decreases by 6°C/km)

6. The temperature at the top of Mount Everest is about 54°C colder.

9km x 6°C/km = 54°C

7. In 1982, Larry Walters rose to an altitude of approximately 4900m (just over 3 miles) on a lawn chair attached to 45 helium-filled weather balloons. Give two reasons why Walters’s efforts were dangerous.7. Walters’s efforts were dangerous because the oxygen content of the air is considerably lower at that altitude and the temperature is extremely cold.

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