Energy Balance & Modeling

What is the fundamental assumption of the "Zero-Dimensional" energy balance model?

It treats the Earth as a single point or uniform sphere with a single average temperature, ignoring latitude or altitude differences.

In the basic energy balance model, the Sun and Earth are treated as ideal _ which absorb all incident radiation.

Blackbodies

What does the "Equilibrium Temperature" of the Earth signify in a radiative energy balance model?

The state where the total incoming Solar Shortwave radiation equals the total outgoing Terrestrial Longwave radiation.

What is a "Climate Feedback Loop"?

A process where a change in the initial climate state triggers a secondary mechanism that either amplifies (positive) or dampens (negative) the initial change.

Explain the "Ice-Albedo" feedback loop.

Rising temperatures melt high-albedo ice, revealing darker ocean/land (lower albedo), which absorbs more energy, causing further warming and melting (Positive Feedback).

Is the "Ice-Albedo" feedback loop considered positive or negative, and why?

Positive feedback, because it amplifies the initial warming signal.

How does increasing "Low, Thick Cloud" cover create a feedback loop?

Warming causes evaporation and cloud formation; low thick clouds have high albedo and reflect sunlight, cooling the Earth (Negative Feedback).

What is "Albedo"?

A dimensionless measure of diffuse reflection of solar radiation, ranging from 0 (total absorption) to 1 (total reflection).

What is the average planetary albedo of Earth (approximate value)?

0.3 (or 30

).

Which surface typically has the highest albedo: Open Ocean, Coniferous Forest, or Fresh Snow?

Fresh Snow (Albedo ~0.80 - 0.90).

Which law describes the total power radiated per unit area of a blackbody in terms of its temperature ($j^* = \sigma T^4$)?

Stefan-Boltzmann Law

What type of radiation does the Earth primarily receive, and what type does it emit?

Earth receives Shortwave (Visible/UV) radiation from the Sun and emits Longwave (Infrared) radiation.

What is "Radiative Forcing"?

The difference between incoming energy and outgoing energy at the top of the atmosphere (measured in Watts per square meter), causing the planet to warm or cool.

Would a large volcanic eruption (injecting sulfur aerosols) result in positive or negative radiative forcing?

Negative Forcing (Cooling), because sulfate aerosols reflect incoming solar radiation back to space before it reaches the surface.

What is the primary physical effect of Greenhouse Gases on the energy budget?

They are transparent to incoming shortwave radiation but absorb and re-emit outgoing longwave radiation, trapping heat.

Name the two most abundant Greenhouse Gases in Earth's atmosphere.

Water vapor (H2O) and Carbon dioxide (CO2).

According to the IPCC and energy budget assessments, which component of the Earth system absorbs ~90

of excess heat?

The Oceans.

In the NASA Energy Budget diagram, what is the approximate value of the "Solar Constant" (incoming radiation) averaged over the globe?

~340 Watts per square meter (The solar constant is ~1360, divided by 4 for the spherical surface area).

How do "High, Thin Clouds" (Cirrus) primarily affect the energy budget?

They transmit most sunlight but absorb outgoing infrared radiation from the surface, creating a net warming effect (Positive Forcing).

The cooling effect of clouds resulting from the reflection of shortwave radiation is known as _.

Cloud Albedo Forcing.

The warming effect of clouds resulting from the absorption and re-emission of longwave radiation is known as ____.

Cloud Greenhouse Forcing.

What is the "Twomey Effect" regarding aerosols?

Higher aerosol concentrations create clouds with more (but smaller) droplets, increasing the cloud's albedo and lifetime (Cooling Effect).

What is the "Albrecht Effect" regarding aerosols?

Increased aerosols inhibit precipitation (rain), extending the "lifetime" of the cloud, allowing it to reflect sunlight for longer periods.

What is the equation for the "Planetary Equilibrium Temperature"?

$T{eq} = \sqrt[4]{\frac{S(1-A)}{4\sigma}}$ where S is Solar Constant, A is Albedo, and $\sigma$ is Stefan-Boltzmann constant.

Why is Earth's actual average surface temperature (~15 degrees C) warmer than its calculated equilibrium temperature (~-18 degrees C)?

Because the Equilibrium equation ignores the atmosphere; the Greenhouse Effect warms the surface by re-radiating energy downwards.

What is the "Keeling Curve"?

A graph showing the accumulation of atmospheric CO2 measured at Mauna Loa, displaying both the long-term rising trend and seasonal oscillations.

Why does the Keeling Curve show a "zig-zag" pattern every year?

In Northern Hemisphere Spring/Summer, plants bloom and absorb CO2 (level drops); in Winter, plants decay and release CO2 (level rises).

How does the "Sun Elevation Angle" affect the albedo of water?

When the sun is high (overhead), water absorbs most light (low albedo); when the sun is low (sunset), water reflects most light (high albedo/glare).

What was the "Ultraviolet Catastrophe"?

A failure of classical physics predicting that a blackbody would emit infinite energy at high frequencies; it was resolved by Planck's Law (Quantum Mechanics).

What does "Wien's Displacement Law" tell us about the Sun vs. the Earth?

Hotter objects emit peak radiation at shorter wavelengths (Sun = Yellow/Green visible); Cooler objects emit at longer wavelengths (Earth = Thermal Infrared).

In the context of Exoplanet remote sensing, if a planet's "Bond Albedo" increases, what happens to its Equilibrium Temperature?

It decreases (because it is reflecting more energy rather than absorbing it).

What is "Back Radiation" in the Earth's energy budget?

Longwave infrared energy emitted by the atmosphere (greenhouse gases/clouds) downward toward the surface.

What is "Latent Heat Flux" (Evapotranspiration) in the energy budget?

Energy transferred from the surface to the atmosphere when water changes phase from liquid to gas (cooling the surface).

What is "Sensible Heat Flux" in the energy budget?

Energy transferred from the surface to the atmosphere via conduction and convection (direct heating of the air).

What are "Aerosols" and what is their direct radiative effect?

Tiny solid/liquid particles in the air; most (like sulfates) scatter sunlight causing cooling, but some (like Black Carbon) absorb sunlight causing warming.

What is the "Zwally Effect" in glaciology?

Surface meltwater drains through cracks (moulins) to the base of an ice sheet, lubricating the bedrock and causing the glacier to slide faster into the ocean.

What is "Carbon Capture and Sequestration" (CCS)?

Technologies designed to capture CO2 emissions from power plants/industry and store them underground so they do not enter the atmosphere.

What is the "Dry Adiabatic Lapse Rate"?

The rate at which a parcel of dry air cools as it rises and expands (~9.8 degrees C per km); crucial for understanding cloud formation height.