UC Berkeley: EPS 7 Midterm 2 Flashcards

Questions and Answers

The optical depth τ for some path of light through a gas depends on...

The length Δz of the light path

The density ρ of the gas

A constant k describing how readily the gas tends to absorb or scatter radiation

All of the above (correct)

Why is the sky blue?

Gas molecules scatter short wavelengths more than long wavelengths.

What does optically thin mean?

Transparent

Small optical depth τ ≪ 1 corresponds to being?

Optically thin Signup and view all the answers

What do we call the layer of the sun that emits light to space?

Photosphere Signup and view all the answers

Large optical depth τ ≫ 1 corresponds to being?

Optically thick Signup and view all the answers

From what optical depth into the Sun does the Sun emit light to space?

τ = 1 Signup and view all the answers

How deep into a gas does the gas emit radiation like a solid surface?

τ = 1 Signup and view all the answers

What color are clouds as seen from space?

White because water drops and ice scatter all wavelengths. Signup and view all the answers

What does optically thick mean?

Opaque Signup and view all the answers

Which of the following is not a greenhouse gas?

Nitrogen Signup and view all the answers

Who is credited with identifying the gases responsible for the greenhouse effect?

John Tyndall Signup and view all the answers

The effective height of long wave emission to space is at 9km where the temperature is 210K on a planet. If the lapse rate in the planet's dry atmosphere is 10K/km, what is the surface temperature?

300K Signup and view all the answers

What is Rayleigh scattering?

Scattering of light caused by atmospheric particles smaller than the wavelength being scattered. Signup and view all the answers

What is Mie Scattering?

Scattering of light caused by atmospheric particles the same size as the wavelength being scattered. Signup and view all the answers

Which gas is transparent to long wave radiation?

Oxygen Signup and view all the answers

Who is credited with postulating the existence of a greenhouse effect and thereby kicking off the field of climate science?

Joseph Fourier Signup and view all the answers

What strongly absorbs long wave radiation?

Water vapor Signup and view all the answers

What gas is relatively opaque to long wave radiation?

Carbon dioxide Signup and view all the answers

In what year was the greenhouse effect postulated, thereby initiating the field of climate science?

1824 Signup and view all the answers

On planet Cruftulon, the effective height of long wave emission to space is 3 km where the temperature is 310 K. If the lapse rate in this atmosphere is 10 K/km, what is the surface temperature?

340K Signup and view all the answers

What best describes the atmospheric greenhouse effect?

The atmosphere lets shortwave pass through but greenhouse gases readily absorb longwave. Signup and view all the answers

Which causes the greater amount of additional warming?

An increase of CO2 from 300 to 400 ppm. Signup and view all the answers

If Earth's mean temperature increases from 288 K to 291 K when CO2 is doubled from its preindustrial concentration, what mean temperature would you expect if CO2 were quadrupled from its preindustrial concentration?

294K Signup and view all the answers

What is the modern estimate for the likely range of Earth's climate sensitivity?

1.5 to 4.5K Signup and view all the answers

Climate sensitivity is the...

Change in temperature for a doubling of CO2. Signup and view all the answers

Who is credited with alerting the public to global warming with his congressional testimony?

James Hansen Signup and view all the answers

What is the mean of 0, 4, and 8?

4 Signup and view all the answers

What was the preindustrial concentration of carbon dioxide?

280ppm Signup and view all the answers

Who first predicted global warming and made a calculation of Earth's climate sensitivity?

Svante Arrhenius Signup and view all the answers

Why is the amount of oxygen in the atmosphere decreasing?

Oxygen is being reacted with carbon to make carbon dioxide. Signup and view all the answers

What is the modern best estimate of Earth's climate sensitivity?

3K Signup and view all the answers

Who is credited with alerting scientists to global warming by documenting the rising concentrations of carbon dioxide in the atmosphere?

Dave Keeling Signup and view all the answers

The first prediction of global warming was made in what year?

1896 Signup and view all the answers

In what year did congressional testimony first raise public awareness about global warming?

1988 Signup and view all the answers

In what decade did measurements on Mauna Loa first document rising concentrations of CO2?

1960s Signup and view all the answers

What was the preindustrial CO2 concentration?

280ppm Signup and view all the answers

Equation for surface temperature is...

T + (lapse rate) x height Signup and view all the answers

What do we call a situation where wind is actively blowing sand onto and off of the sand dune, but the height of the sand dune is not changing in time?

Steady state Signup and view all the answers

A positive forcing is...

An externally applied increase in the net inflow. Signup and view all the answers

What word do we ascribe to a sand dune that has no grains of sand being added or removed?

Static equilibrium Signup and view all the answers

A positive perturbation is...

An increase in the stock from its steady-state level. Signup and view all the answers

A negative forcing is...

An externally applied reduction in the net inflow. Signup and view all the answers

A negative perturbation is...

A decrease in the stock from its steady-state level. Signup and view all the answers

If the Earth suddenly becomes warmer than its steady-state temperature, the Planck feedback tends to make the Earth?

Cooler Signup and view all the answers

Which of the following is not a positive feedback?

Lapse-rate feedback Signup and view all the answers

The radiative forcing by extra greenhouse gases is best described as causing...

A decrease of outgoing power. Signup and view all the answers

As the Earth warms, the atmosphere holds water vapor and that tends to cause the Earth to emit radiation to space.

More and less Signup and view all the answers

What is the Earth's biggest negative feedback?

Planck feedback Signup and view all the answers

Why does burning fossil fuels cause global warming?

The extra atmospheric CO2 lifts the τ = 1 layer to a colder level in the atmosphere. Signup and view all the answers

With respect to Earth's temperature, an increase in CO2 in the atmosphere can be described as a ____

Positive forcing Signup and view all the answers

What is the Earth's biggest positive feedback?

Water vapor feedback Signup and view all the answers

If the Earth suddenly becomes cooler than its steady-state temperature, the Planck feedback tends to make the Earth?

Warmer Signup and view all the answers

As the Earth cools, the atmosphere holds water vapor and that tends to cause the atmosphere to emit radiation to space.

Less and more Signup and view all the answers

Is the ice-albedo feedback a positive or negative feedback?

Positive Signup and view all the answers

Final perturbation = ...

Forcing / |feedback parameter| Signup and view all the answers

If a sand dune's feedback parameter is +1 kg/s/m, what is the final perturbation if a forcing of -2 kg/s is applied?

Nonsense question because the dune is unstable (positive feedback parameter) Signup and view all the answers

Net rate = ...

Flow in - flow out Signup and view all the answers

If a sand dune's feedback parameter is +25 kg/s/m, by what amount does its net rate of inflow change if we apply a sudden height perturbation of −5 m?

-125 kg/s Signup and view all the answers

If a sand dune's feedback parameter is −5 kg/s/m, what happens if we suddenly add 4 m of sand?

It will go back to its original steady state Signup and view all the answers

If a sand dune's feedback parameter is −3 kg/s/m, what is the final perturbation if a forcing of −9 kg/s is applied?

-3 m Signup and view all the answers

If a sand dune's feedback parameter is +24 kg/s/m, by what amount does its net rate of inflow change if we apply a sudden height perturbation of 2 m?

48 kg/s Signup and view all the answers

If a sand dune's feedback parameter is −15 kg/s/m, by what amount does its net rate of inflow change if we apply a sudden height perturbation of 3 m?

-45 kg/s Signup and view all the answers

If a sand dune's feedback parameter is −8 kg/s/m, what is the final perturbation if a forcing of 4 kg/s is applied?

0.5 m Signup and view all the answers

If the height of a sand dune is 50 meters and the net inflow of sand is 10 kg/s, what can we say about this sand dune?

It is not in steady state Signup and view all the answers

If a sand dune's feedback parameter is +8 kg/s/m, what happens if we suddenly reduce the height of the dune by 2 m?

It will disappear Signup and view all the answers

If a sand dune's feedback parameter is −20 kg/s/m, by what amount does its net rate of inflow change if we apply a sudden height perturbation of −4 m?

80 kg/s Signup and view all the answers

Who created the cloud classification scheme that we still use today?

Luke Howard Signup and view all the answers

When was most coal formed?

Carboniferous period 300 Mya Signup and view all the answers

What is the empirical formula for coal?

C or CH Signup and view all the answers

Photosynthesis is best described by what chemical reaction?

CO2 + H2O + photon → O2 + CH2O Signup and view all the answers

What is another way to write 300 Mya?

0.3 Gya Signup and view all the answers

Oil is...

Fossilized plankton Signup and view all the answers

What is peat?

Soggy swamp soil Signup and view all the answers

What is plankton?

Any collection of microscopic organisms that drift in the sea. Signup and view all the answers

What is 3 Gya?

3 billion years ago Signup and view all the answers

What is the empirical formula for gas?

CH4 Signup and view all the answers

Natural gas is...

Fossilized plankton Signup and view all the answers

When was the universe formed?

14 Gya Signup and view all the answers

Atmospheric CO2 decreases most rapidly in...

Northern-Hemisphere summer Signup and view all the answers

What is the empirical formula for oil?

CH2 Signup and view all the answers

Coal is...

Fossilized peat Signup and view all the answers

When was most oil formed?

Jurassic period 150 Mya Signup and view all the answers

Respiration is best described by what chemical reaction?

O2 + CH2O → CO2 + H2O + photon Signup and view all the answers

January is during the Southern Hemisphere's...

Summer Signup and view all the answers

Which is not a contributing factor to the seasonal cycle in atmospheric CO2?

CO2 is a greenhouse gas. Signup and view all the answers

When the Northern Hemisphere is in summer, the Southern Hemisphere is in...

Winter Signup and view all the answers

What causes the seasons?

The Earth's axis of rotation is tilted with respect to Earth's orbital plane. Signup and view all the answers

When was the Earth formed?

4.5 Gya Signup and view all the answers

Roughly how much of the recoverable coal have humans used?

A few percent Signup and view all the answers

What is roughly the per-capita consumption of coal in the United States?

3 tons/year Signup and view all the answers

How much fossil fuel have humans burned?

400 GtC Signup and view all the answers

Roughly at what rate are the ocean and plants absorbing CO2 at present?

5 GtC/year Signup and view all the answers

Roughly how much of the recoverable oil have humans used?

Half Signup and view all the answers

What is a GtC?

A billion tons of carbon Signup and view all the answers

How many GtC were there in the preindustrial atmosphere?

600 GtC Signup and view all the answers

What is the current concentration of atmospheric CO2?

400 ppm Signup and view all the answers

If the concentration of atmospheric CO2 increases by 100 ppm, roughly how much more carbon is there in the atmosphere?

200 GtC Signup and view all the answers

In a business-as-usual scenario, what is a likely concentration of atmospheric CO2 in the year 2100?

1000 ppm Signup and view all the answers

If the amount of CO2 in the atmosphere increases by 100 GtC, roughly how much does the concentration of CO2 increase?

50 ppm Signup and view all the answers

Study Notes

Optical Depth and Light Interaction

Optical depth (τ) is determined by the light path length (Δz), gas density (ρ), and a constant (k) specific to the gas's absorption/scattering characteristics.
Optically thin means the medium is transparent; this corresponds to a small optical depth (τ ≪ 1).
Optically thick means the medium is opaque, corresponding to a large optical depth (τ ≫ 1).

Atmospheric Phenomena

The sky's blue color results from gas molecules scattering short wavelengths of light more effectively than long wavelengths.
Clouds appear white from space as water drops and ice scatter all wavelengths of light.

Greenhouse Effect and Climate Science

The layer of the sun emitting light into space is called the photosphere; emission occurs at an optical depth of τ = 1.
John Tyndall identified gases responsible for the greenhouse effect; Joseph Fourier postulated the greenhouse effect's existence, founding climate science.
Major greenhouse gases include water vapor and carbon dioxide, with nitrogen not classified as a greenhouse gas.

Climate Sensitivity and Global Warming

Climate sensitivity measures temperature changes in response to doubling CO2 levels; modern estimates range from 1.5 to 4.5K, with a best estimate of 3K.
James Hansen raised public awareness of global warming through congressional testimony in 1988; Svante Arrhenius first predicted global warming in 1896.
CO2 concentration preindustrial levels were around 280 ppm; currently approximately 400 ppm.

Feedback Mechanisms

Positive feedback examples include water vapor feedback and ice-albedo feedback, causing amplifying warming effects.
Negative feedback is exemplified by Planck feedback, which acts to cool the planet in response to warming.
Changes in atmospheric conditions due to fossil fuel combustion elevate the CO2 layer to colder atmospheric levels, increasing greenhouse effect impact.

Perturbations and Steady States

Perturbations can be either positive (adding stock to the system) or negative (removing stock); final perturbation is calculated using forcing and feedback parameters.
Steady state exists when inflow and outflow are balanced, while static equilibrium occurs with no change in stock.

Carbon and Fossil Fuels

Fossil fuels like coal and oil originate from ancient organic materials; coal is fossilized peat formed mainly during the Carboniferous period, while oil is from fossilized plankton predominantly from the Jurassic period.
A significant portion of CO2 reduction occurs in the Northern Hemisphere summer, as plant photosynthesis peaks.

Temporal Context and Historical Data

The Earth formed about 4.5 billion years ago (Gya), while most coal was created around 300 million years ago (Mya).
Humans have utilized only a few percent of recoverable coal, with per-capita consumption in the U.S. roughly 3 tons/year.
Approximately 400 gigatons of carbon (GtC) have been burned by humans, with current absorption rates by oceans and plants around 5 GtC/year.

Environmental Implications

Future projections suggest atmospheric CO2 could reach 1000 ppm by 2100 without changes in environmental policies.
An increase of 100 ppm CO2 concentration correlates with an addition of about 200 GtC to the atmosphere, affecting climate conditions.

Chemical Reactions and Biological Processes

Photosynthesis is represented as CO2 + H2O + photon → O2 + CH2O, while respiration reverses this process: O2 + CH2O → CO2 + H2O + photon.

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Description

Test your knowledge with these flashcards from UC Berkeley's EPS 7 course. This quiz covers key concepts related to optical depth, light scattering, and atmospheric phenomena. Perfect for reviewing essential terms and definitions before your midterm exam.