Astronomy Final Study

The following images show the four terrestrial planets in our solar system. Rank the planets from left to right based on the amount by which the greenhouse effect increases their surface temperatures, compared to what their temperatures would be without the greenhouse effect, from largest to smallest increase.

(LARGEST INCREASE) Venus, Earth, Mars, Mercury (SMALLEST INCREASE)

All the following statements are true. Which two represent the two facts that lead us to expect Earth to be warming up as a result of human activity? Be sure to choose two of the statements below.

- Greenhouse gases make Earth warmer than it would be otherwise. - Human activity is increasing the concentration of carbon dioxide and other greenhouse gases in the atmosphere.

Which of the following is not an expected consequence of the rising carbon dioxide concentration or global warming?

Animal deaths due to carbon dioxide poisoning.

Which of the following is not a characteristic of the seasons on Mars?

As on Earth, the seasons are caused primarily by axis tilt and orbital distance has virtually no effect.

Greenhouse gases in the atmosphere, such as carbon dioxide and water vapor, make Earth warmer than it would be otherwise because these gases

absorb infrared light emitted by the surface

Why does Earth have so little carbon dioxide in its atmosphere compared to Venus?

Earth has just as much carbon dioxide as Venus, but most of it is locked up in carbonate rocks rather than being free in the atmosphere.

Greenhouse gases in the atmosphere, such as carbon dioxide and water vapor, make Earth warmer than it would be otherwise because these gases __________.

absorb infrared light emitted by the surface

Scientists have confidence in the predictions of today's best climate models because they

agree well with actual data for recent decades

Scientists have confidence in the predictions of today's best climate models because they __________.

agree well with actual data for recent decades

What happens to the energy that the ground absorbs in the form of visible sunlight?

It is returned upward in the form of infrared light.

On a cloudless day, what happens to most of the visible light headed toward Earth?

It reaches Earth's surface, where some is reflected and some is absorbed.

In the context of Earth's climate history, what do we mean by snowball Earth?

It refers to a very deep ice age that occurred hundreds of millions of years ago.

What is the importance of the carbon dioxide (CO2) cycle?

It regulates the carbon dioxide concentration of our atmosphere, keeping temperatures moderate.

How did molecular oxygen (O2) get into Earth's atmosphere?

It was released by life through the process of photosynthesis.

What is the leading hypothesis for Venus's lack of water?

Its water molecules were broken apart, and hydrogen was lost to space.

In which direction do hurricanes in the Southern Hemisphere rotate?

clockwise

Gas particles in Earth's atmosphere most easily escape from the __________

exosphere

Earth has been gradually warming over the past few decades. Based on a great deal of evidence, scientists believe that this warming is caused by _____.

human activities that are increasing the concentration of greenhouse gases in Earth's atmosphere

The greenhouse effect raises Earth's surface temperature (from what it would be otherwise) because the infrared light radiated by Earth's surface

is absorbed by greenhouse gases, slowing the escape of this energy to space

The greenhouse effect raises Earth's surface temperature (from what it would be otherwise) because the infrared light radiated by Earth's surface __________.

is temporarily absorbed by greenhouse gases and then reemitted in random directions

What kind of gas is most affected by thermal escape?

light gases

Where is most of the CO2 that has outgassed from Earth's volcanoes?

locked up in rocks

Most of the charged particles from the Sun are deflected around Earth by the _______

magnetosphere

Which of the following is not a greenhouse gas?

oxygen (O2)

What causes the release of oxygen into Earth's atmosphere?

photosynthesis

Which two factors are critical to the existence of the carbon dioxide (CO2) cycle on Earth?

plate tectonics and liquid water oceans

Earth's ______ absorbs most of the ultraviolet light arriving here from the Sun.

stratosphere

Which region of Earth has warmed the most in recent decades?

the Arctic

Which characteristic of Earth explains why we have an ultraviolet-absorbing stratosphere?

the existence of photosynthetic life

Most of the X-rays coming from the Sun are absorbed in the _______

thermosphere

The densest layer of the atmospheres of Venus, Earth, and Mars is the _______

troposphere

The greenhouse effect occurs in the

troposphere

Which of the following correctly lists the layers of Earth's atmosphere from the ground upward?

troposphere, stratosphere, thermosphere, exosphere

What kind of light warms the stratosphere?

ultraviolet

The average temperature over the past 1000 years has been about 15∘C. From the graphs, you can conclude that Earth's average temperature during the past 800,000 years has

varied between about 7∘C and 19∘C

The average temperature over the past 1000 years has been about 15∘C. From the graphs, you can conclude that Earth's average temperature during the past 800,000 years has __________.

varied between about 7∘C and 19∘C

The energy that warms Earth's surface comes primarily in the form of

visible light from the Sun

The energy that warms Earth's surface comes primarily in the form of __________.

visible light from the Sun

Earth's temperature remains fairly steady, which means that Earth must return nearly the same amount of energy to space that it receives from the Sun. In what form(s) does Earth return most of this energy to space?

visible light reflected by the surface infrared light emitted by the surface and atmosphere visible light reflected by clouds

Earth's temperature remains fairly steady, which means that Earth must return the same amount of energy to space that it receives from the Sun. In what forms does Earth return most of this energy to space?

visible light reflected by the surface, reflected by clouds, and infrared light emitted by the surface and atmosphere

Which of the following is a strong greenhouse gas?

water vapor

Suppose that Earth's atmosphere had no greenhouse gases. Then Earth's average surface temperature would be _______.

well below the freezing point of water

Which of the following is the most basic definition of a greenhouse gas?

a gas that absorbs infrared light

What important change in the Sun over the past four billion years is thought to be very important to understanding the climates of Venus, Earth, and Mars?

a gradual brightening with time

What do we mean by a runaway greenhouse effect?

a greenhouse effect that keeps getting stronger until all of a planet's greenhouse gases are in its atmosphere

What is a magnetosphere?

a region of space around a planet in which the planet's magnetic field can trap charged particles

On the graphs shown, you can identify an ice age by looking for

a trough (bottom of a dip) on the temperature graph

On the graphs shown, you can identify an ice age by looking for __________.

a trough (bottom of a dip) on the temperature graph

Suppose we represent Earth with a basketball. On this scale, most of the air in Earth's atmosphere would fit in a layer that is _________.

about the thickness of a sheet of paper

Although the data show only a correlation between the carbon dioxide concentration and the global average temperature, scientists have other reasons to think that a rise in the carbon dioxide concentration actually causes a rise in the global average temperature. All of the following statements are true. Which statements lend support to the idea that carbon dioxide is a cause of planetary warming? Check all that apply.

-Models of the greenhouse effect successfully predict the temperatures of Venus and Mars from their atmospheric carbon dioxide amounts. -We understand the physical mechanism of the greenhouse effect, through which carbon dioxide can increase a planet's temperature. -Models of Earth's climate that include recent increases in the carbon dioxide concentration match observed temperature increases better than those that do not include it.

Earth's temperature remains fairly steady, which means that Earth must return nearly the same amount of energy to space that it receives from the Sun. In what forms does Earth return most of this energy to space? Check all that apply.

-infrared light emitted by the surface and atmosphere -visible light reflected by clouds -visible light reflected by the surface

1. Most of the charged particles from the Sun are deflected around Earth by the 2. Earth's absorbs most of the ultraviolet light arriving here from the Sun. 3. Most of the X-rays coming from the Sun are absorbed in the 4. Gas particles in Earth's atmosphere most easily escape from the 5. The densest layer of the atmospheres of Venus, Earth, and Mars is the

1. magnetosphere 2. stratosphere 3. thermosphere 4. exosphere 5. troposphere

Make a prediction: If the rise in carbon dioxide concentration continues at its current pace, the concentration in the year 2050 will be about _____ parts per million.

460

All of the following have occurred over long periods of time on Earth. Which one is not thought to have played a major role in long-term changes in Earth's climate?

A gradual rise in the atmospheric content of oxygen.

Which of the following best describes how the greenhouse effect works?

A planet's surface absorbs visible sunlight and returns this absorbed energy to space as infrared light. Greenhouse gases slow the escape of this infrared radiation, which thereby heats the lower atmosphere.

In the context of a planetary atmosphere, what is a bar?

A unit of pressure roughly equal to the atmospheric pressure at sea level on Earth.

Why is the Coriolis effect so weak on Venus?

Because Venus rotates so slowly.

Why is the sky blue (on Earth)?

Because molecules scatter blue light more effectively than red light.

Why is thermal escape of atmospheric gas much easier from the Moon than from Earth?

Because the Moon's gravity is so much weaker than Earth's.

Why is Mars red?

Chemical reactions between surface rock and atmospheric oxygen literally rusted the surface.

Suppose Earth were to cool down a little. How would the carbon dioxide cycle tend to restore temperatures to normal?

Cooler temperatures lead to slower formation of carbonate minerals in the ocean, so carbon dioxide released by volcanism builds up in the atmosphere and strengthens the greenhouse effect.

In Part A, you found that Earth emits only infrared light. This infrared light can be absorbed by greenhouse gases, such as carbon dioxide and water vapor, in the atmosphere. In fact, all the terrestrial planets emit infrared light from their surfaces. The following images show the four terrestrial planets in our solar system. Rank these planets from left to right based on the total amount of infrared-absorbing greenhouse gases in their atmospheres, from greatest to least.

Greatest to least Venus, Earth, Mars, Mercury

The following images represent four types (wavelength bands) of light. Rank these from left to right based on the amount of each that is emitted (as thermal radiation) by Earth's surface, from greatest to least. If you think that two (or more) types should be ranked as equal, drag one on top of the other(s) to show this equality.

Greatest: infared (Xray, visible, UV) equal

Observations indicate that the Moon has water ice in craters near the poles. Where do scientists suspect this water came from?

Ice brought by comet impacts long ago.

How is it possible that the Moon might have some water ice today?

Ice brought by comet impacts may be frozen in craters near the Moon's poles.

All the following statements about Mars are true. Which one might have led to a significant loss of atmospheric gas to space?

Mars lost any global magnetic field that it may once have had.

When were the heat-trapping effects of gases that cause the greenhouse effect first measured by scientists?

More than 150 years ago.

Why do we think that Venus has so much more atmospheric gas than Earth?

Most of the gases that have been released from volcanoes on Earth later returned to the surface.

Does Venus have auroras around its poles, like Earth? Why or why not?

No, because it lacks a global magnetic field.

The following images show the four terrestrial planets in our solar system. Rank the planets from left to right based on the strength of the greenhouse effect occurring at their surfaces, from strongest to weakest.

Strongest to weakest: Venus, Earth, Mars, Mercury

All the following statements are true. Which one explains why convection can occur in the troposphere but not in the stratosphere?

Temperature declines with altitude in the troposphere but increases with altitude in the stratosphere.

Deuterium is much more abundant on Venus than Earth. What do we think this fact tells us about Venus?

That it has lost a tremendous amount of water as a result of molecules being split by ultraviolet light and the hydrogen escaping to space.

What makes us think that Mars must once have had an atmosphere that was warmer and had higher surface pressure?

The atmosphere is too cold and thin for liquid water today, yet we see evidence of flowing water in the past.

Based on the evidence that atmospheric carbon dioxide is a cause of planetary warming, what aspect of the graphs should most concern us?

The carbon dioxide concentration today is significantly higher than at any time in the past 800,000 years and is rapidly rising.

On a day with complete cloud cover, what happens to the visible light headed toward Earth?

The clouds reflect much of it back to space, though some still reaches the surface.

Which of the following is not an expected consequence of global warming?

The entire Earth will warm up by the same amount.

Based on everything we have learned about Venus and Mars, what is the most surprising aspect of Earth's climate history?

The fact that the temperature of our planet has remained relatively steady throughout our planet's history.

Which of the following statements about ozone (in Earth's stratosphere) is not true:

The presence of ozone was crucial to the origin of life some 4 billion years ago.

Which of the following general statements about Earth's atmosphere is not true?

The sea level temperature depends primarily on the total amount of gas in our atmosphere.

Suppose that Earth's ice caps melted, but everything else about the Earth's surface and atmosphere stayed the same. What would happen to Earth's average surface temperature?

The surface temperature would increase.

Why does atmospheric pressure decrease as you go higher in altitude on Earth?

The weight of the atmosphere above you decreases with altitude.

Notice that the peaks and troughs on the temperature graph occur at the about the same times as peaks and troughs on the carbon dioxide graph. What can we infer from this fact alone?

There is a correlation between the carbon dioxide concentration and the global average temperature.

According to scientists, the naturally occurring greenhouse effect makes Earth about 31∘C warmer than it would be if there were no greenhouse gases in our atmosphere. How do scientists "know" what Earth's temperature would be without greenhouse gases?

They calculate this temperature from Earth's reflectivity and distance from the Sun.

Which of the following best describes the nature and origin of the atmospheres of the Moon and Mercury?

They have thin exospheres only, with gas coming from impacts of subatomic particles and photons.

In very general terms, how do the temperature structures of the atmospheres of Venus and Mars differ from that of Earth?

They lack ultraviolet-absorbing stratospheres.

Which of the following describes a primary role of global circulation cells in a planet's atmosphere?

They transport heat from the equator toward the poles.

If Earth had as much carbon dioxide in its atmosphere as Venus, our planet would be too hot for liquid water to exist on the surface.

True

Which of the following best explain what we think happened to outgassed water vapor on Venus?

Ultraviolet light split the water molecules, and the hydrogen then escaped to space.

Which terrestrial world has the most atmosphere?

Venus

Which planet(s) have an atmosphere that consists mostly of carbon dioxide?

Venus and Mars

All of the following statements are true. Which one provides strong observational support for the claim that greenhouse gases make a planet warmer than it would be otherwise?

Venus has a higher average temperature than Mercury.

All the statements below are true. Which one gives the primary reason why the surface of Venus today is some 450°C hotter than the surface of Earth?

Venus has a much stronger greenhouse effect than Earth.

Which of the following correctly lists the terrestrial worlds in order from the thickest atmosphere to the thinnest atmosphere? (Note: Mercury and the Moon are considered together in this question.)

Venus, Earth, Mars, Moon/Mercury

Which of the following general statements about light and Earth's atmosphere is not true?

Visible light from the Sun is absorbed in the exosphere.

Which of the following is not caused by the Coriolis effect on Earth?

Water going down a drain swirls in opposite directions in the northern and southern hemispheres.

Based solely on an understanding of the greenhouse effect (as displayed in the figure), which one of the following statements is true?

We should expect an increase in the greenhouse gas concentration to lead to global warming.

Although the data show only a correlation between the carbon dioxide concentration and the global average temperature, scientists have other reasons to think that a rise in the carbon dioxide concentration actually causes a rise in the global average temperature. All of the following statements are true. Which statements lend support to the idea that carbon dioxide is a cause of planetary warming?

We understand the physical mechanism of the greenhouse effect, through which carbon dioxide can increase a planet's temperature. Models of the greenhouse effect successfully predict the temperatures of Venus and Mars from their atmospheric carbon dioxide amounts. Models of Earth's climate that include recent increases in the carbon dioxide concentration match observed temperature increases better than those that do not include it.

What is the difference between weather and climate?

Weather refers to short-term changes in wind, rain, and temperature, while climate refers to the long-term average of weather.