Climate Change Exam 1

List Earth's "spheres"

__Atmosphere:__ air above the earth's surface

__Hydrosphere:__ all LIQUID water
__Cryosphere:__ all FROZEN water
__Biosphere:__ all parts of the earth where life exists
__Lithosphere:__ the solid earth (upper crust and mantle)

Weather vs. Climate

__weather:__ temporary state of the atmosphere
__climate:__ average/trends of weather over longer timescales

* "climate is what you expect, weather is what you get"

Climate Normal

30 year average for a given weather variable
(temperature, precipitation, humidity, etc.)

Standard Deviation

a measure of how spread out data is

* Low: not spread out
* High: very spread out

What does it mean when data falls within "one standard deviation"?

1 standard deviation: ~68%
2 SDs: ~95%
3 SDs: ~99.7%

Climate Change

a change in the long-term average conditions in climate

* "the average temperature in Philadelphia has risen an average of 2 degrees"

Diurnal Cycle of Temperature

24-hour cycle

* Due to the daily rotation, at roughly noon an area is getting the most solar radiation and the highest heat

Seasonal Cycle of Temperature

1 year due to Earth's tilt some parts of the Earth get more direct sunlight

Timeline of Climate

__Paleoclimate:__ earliest, variations caused by orbital parameters and rangers of sun energy
__Pre-industrial:__ started by the last glacial maxima, variations mainly because of glacial cycles
__Anthropogenic:__ current, started by the industrial revolution and an increase in greenhouse gasses & land terraforming

Three Time-Scales

__Short-Term__: daily, monthly, seasonal

__Mid-range:__ annual, decadal (10 years), multi-decadal (>10 years), centennial (100 years)

__Long-term:__ millennia (thousands), millions of years, billions of years

Which time scales are the most immediately relevant to human life?

short-term and mid-term

Modes of Natural Variability

natural shifts in the climate that occur (not concerning)

Climate Variability

the short-term variations in the climate system (relative to the time scale of interest)

* When looking at climate change, we want to know if events are outside the normal variability

Latitude Impacts on Temperature

closer to the equator = more intense solar radiation, higher temperatures

* Locations near the poles have more atmosphere for energy to break through

Latitude’s Impacts on Seasonality

further from the equator = more pronounced seasonal changes

* they move the most, while the equator is usually always facing directly at the sun

Altitude’s Impacts on Temperature

higher altitude, colder temperature

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Topography’s Impacts on Weather

* Mountains act as barriers to atmospheric circulation


* Air is forced to climb higher, making it cooler


* Cool air can’t hold as much water, causing clouds and then rain

Rain Shadow

a dry area that receives little rainfall due to its position near mountains

* As air rises, it can’t hold as much water, so at the top of a mountain it is wet and has lots of precipitation
* by the time it gets to the other side of the mountain, the air can lower and heat up, meaning less precipitation

Topography’s Impacts on Weather __by Hemisphere__

The Northern hemisphere has more mountains than the Southern hemisphere

* Fewer mountains mean more winds, because it doesn’t have mountains to interrupt the flow of air

The Lake Effect

impacts a region sitting next to a warm body of water

* cold air moves over a warm lake, causing heat and moisture to transfer from the water to the atmosphere
* leads to cloud formation and lots of precipitation as it moves over the other side of the lake

specific heat

the heat required to raise the temperature of a unit of something

Ocean Currents’ Influences on Climate

warm vs cold currents impact how humid/dry the area is

* CA sits near a cold current (California Current), meaning it is cool and dry
* FL sits next to a warm current (Gulf Stream), meaning it is hot and humid

this is what allows Europe to be warmer than Canada despite being at the same latitude

Prevailing winds

* winds that blow consistently in a given direction over a particular region on Earth
* due to factors such as uneven heating from the Sun and the Earth's rotation, these winds vary at different latitudes on Earth

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determines which type of air mass typically moves over an area

Which regional climate controls can change on human time scales as the planet warms?

Ocean currents, Prevailing winds

States of Climate

* __Steady-State__: a stable climate where variability is relatively short-lived; no external forces changing the climate in one way or another
*  the system always returns to the same state despite small changes
* The rate of change in temperature/precipitation/etc is 0
* __Forced (transient) state__: a climate that is undergoing a transition due to changes in an entity outside of the earth's system
* Human intervention: industrial properties (recent)
* Orbital changes (long ago)

Climate Forcing

any agent, entity, or influence that forces the climate into another state

Natural Climate Forcing (def and list)

climate forcing that is NOT directly attributable to human activity

* tectonic processes
* orbital parameter changes
* solar variability
* volcanic eruptions

Orbital Parameter Changes (list)

* __Eccentricity__: change in the shape of Earth’s orbit around the sun
* __Precession__: change in the direction that Earth’s spin axis is pointed (wobble)
* Obliquity: change in the tilt of Earth’s axis

Solar Variability

* changes in the energy output of the sun
* The sunspot cycle affects this
* Cycles are roughly 11 years

Why do volcanic eruptions change climate temporarily?

* inject large amounts of ash and gases into the atmosphere
* Can scatter and absorb incoming solar radiation, cooling Earth’s surface

Anthropogenic Climate Forcing (def & list)

climate forcing caused by human activity

* Greenhouse Gas Emissions
* Aerosols
* Land use change

Greenhouse Gases Climate Forcing

* trap heat in the atmosphere by strongly absorbing and re-emitting infrared radiation
* increase temperature
* CO2, CH4, CFCs, N2O, O

Aerosols’ Impact on Climate

* Aerosols injected into the lower atmosphere absorb and scatter incoming radiation
* tend to cool the planet
* Factories, trucks, furnaces, fireplaces

Land Use Change

* modification of the Earth’s surface, changes the reflectivity (__albedo__) of the surface; changes the amount of radiation that gets reflects into space
* Deforestation, desertification
* Depending on what it is, it can either be warming or cooling

Radiation

energy transmitted as electromagnetic waves

What do electromagnetic waves need to travel/propogate?

nothing! they don’t require a medium

* can just travel through space

Frequency vs Wavelength

__Frequency__: # of oscillations a given amount of time

__Wavelength__: length of a wave

Perfect Black Body

* an object that absorbs and emits radiation at **all wavelengths**
* Absorbs all of its energy, heats up to a certain temperature, and then reradiates that energy
* The sun and Earth are almost perfect blackbodies

Where is the sun’s peak intensity?

visible light spectrum

Wein’s Law

The **peak emission wavelength** of an object depends on the object’s temperature

* λmax: peak wavelength
* T: object’s temperature (units: K)
* C: a constant equal to 2898 μm K

The Earth emits mostly what type of electromagnetic wave?

infrared

The total energy emitted from an object is equal to what on a graph?

the shaded area under each curve on a radiation flux graph

Stephan Boltzmann’s Law

The **total energy flux per area** emitted from a black body depends on its temperature

* E = energy flux
* 𝜀 = a measure of the object's departure from the “perfect emitter”
* A number will be given when we do calculations
* 𝜎= Stephan Boltzmann's constant (5.67 x 10^-8 units J/sK^4m^2)

1 Watt = ?

1 J/s (joule per second)

Energy flux

the rate of transfer of energy through a surface

Energy Budget Model

the balance between the amount of energy that flows in and out from Earth

* energy, mass, matter

Heating & Cooling Degree Days

a measure of how much energy is being used to heat/cool a building

* not a unit of time, but a measure of temperature
* Deviation from 65 degrees Fahrenheit

Calculating the Earth’s Energy Budget (list steps)

1. Find the total energy leaving the Sun
2. Find the total solar energy that reaches the Earth
3. Find the total energy from the Sun that hits Earth’s surface; **incident radiation**
4. Calculate how much of the incident radiation is absorbed/reflected; **albedo**


1. Calculate how much energy is emitted from the Earth’s surface

Finding the Earth’s Energy Budget: **Total Energy Leaving the Sun**

Stephan Boltzmann’s Law

* this answer is energy per square unit
* you then **multiply it by the entirety of the Sun’s surface area**
* Qsun = total energy leaving the sun
* the sun’s albedo 𝜀 is \~1
* 4𝜋𝑅𝑠𝑢𝑛^4 is the surface area
* 𝜀𝜎𝑇𝑠𝑢𝑛^4 comes from SBL

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Unit: Watts

Finding the Earth’s Energy Budget: **Total Solar energy that** ***reaches*** **Earth**

Qsun = total energy leaving the sun

D = distance from Earth to sun

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Unit: W/m^2

Solar Constant

derived from the equation for finding the total energy leaving the sun that **reaches the earth**

Finding the Earth’s Energy Budget: **Finding the total energy leaving the sun that** ***hits*** **Earth’s surface**

AKA “Incident Radiation”

* Solar constant x the area of a circle (the surface of the Earth hit by the Sun)

Incident Radiation

the amount of energy that actually hits the earth (or another object)

Finding the Earth’s Energy Budget: **Finding how much of the incident radiation is absorbed vs. reflected out to space**

AKA “Albedo”

* the fraction of energy reflected by a surface
* The average albedo of the earth is \~0.3
* (1-𝛼) x Incident Radiation
* (1-𝛼) : the amount **absorbed** because albedo is the amount reflected

Albedo

* the fraction of energy **reflected** by a surface
* Dark colors are close to 0
* Pale colors are close to 1

In terms of albedo, why are we concerned about losing ice?

losing ice gets rid of some of our brighter surfaces, meaning that more energy will be absorbed

* albedo will go down

Finding the Earth’s Energy Budget: **Finding how much energy the Earth emits**

* same as the Sun’s equation
* E𝑒𝑎𝑟𝑡ℎ is the energy flux (SB Law)
* 4𝜋𝑅𝑒𝑎𝑟𝑡ℎ^2 is the surface area

In a steady-state, Energy*in* = ?

\-Energy*out*

Finding Global Average Surface Temperature in a Steady-State

Energy in = Energy Out

Greenhouse Effect

retainment of heat due to the greater transparency to visible light than to infrared radiation

* The Sun lets visible light in, but the Earth radiates infrared
* Greenhouse gasses hold in energy and cause the earth to warm up to a habitable state (about 33C); without them, it would be too cold

Vibration Modes

the more a molecule can move when it is hit with radiation, the more it can emit and absorb radiation

* Triatomic+ molecules have multiple ways that they can stretch and bounce around, while diatomic can only move in one way

Radiative Efficiency

the ability to absorb energy

* in relation to greenhouse gasses, certain types are able to absorb more energy due to their shape and ability to move

Residence Time

the amount of time greenhouse gasses remain in the atmosphere

Global Warming Potential (GWP)

* a measure of how much heat each gas traps in the atmosphere
* **Compared to CO2** because it is the most stable and long-lasting
* Over 100 years, how much gas can 1 ton of that gas can absorb energy compared to 1 ton of CO2
* CO2 always has a GWP of 1
* “Methane is 23% more effective at absorbing infrared radiation than CO2 over 100 years”
* Methane has a 23 GWP

How does Residence Time affect with GWP?

a gas with a lower residence time has to continuously replace its supply in the atmosphere, while longer residencies can build up

* *Over time, CO2 can* ***accumulate*** *while CH4 has to be* ***recycled****.*

H2O is a strong greenhouse gas, but why does it have a GWP-100 of 0?

H2O has such a short residency that it doesn’t have the time to have a meaningful effect compared to CO2. It would be a ridiculously small number

CH4 has a higher radiative efficiency than CO2, but a lower residence time. Which would have a higher GWP over 20 years? 10,000 years?

* 20 years: CH4 would have a higher GWP because the residence time has less of an effect; CH4 and CO2 will both be able to accumulate relatively the same amount, meaning that the higher radiative efficiency has a chance to work in CH4’s favor

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* 10,000 years: CO2 would have a higher GWP. CH4’s residence time would prevent its radiative efficiency to have an impact on how much it absorbs because it will need to constantly be replaced

How does increased CO2 (and other greenhouse gasses) cause more extreme weather?

* increased CO2 and other greenhouse gasses absorb more energy, meaning that more heat is trapped within the Earth’s atmosphere
* As atmospheric temperature rises due to global warming, the **atmosphere can hold more water**
* This causes **more extreme rain-related events**, such as hurricanes and flooding.

H2O vs CO2

Positive Feedback Loops

elements are **amplified** by successive loops

Negative Feedback Loops

elements are **dampened** by successive loops

* Example: as Earth’s temperature rises, more radiation comes from the Earth’s surface, and then temperature decreases

Feedback Loops

a process by which something invokes a change in another element, which then impacts the first element again and the loop self perpetuates

Latent Heat

heat exchange/transfer that occurs with a change of phase (solid to liquid to gas of water)

Advection/Convection

thermal energy transfer through the **movement** of fluids (aka “heat transport”)

* ex: ocean currents, warm air rising

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Convection: vertical transport

Advection: horizontal transport

Sensible Heat

thermal energy transfer through molecular contact

* no phase change
* Rate of energy transfer is higher when there is a larger difference between temperature
* Temperature difference = heat transfer
* Touching hand to a hot stove -> transfer of heat

Radiation Cycle

Radiative-Convective Equilibrium

* Air at Earth’s surface warmed via solar radiation **expands** and it takes up moisture via **evaporation**.
* This warm air then **rises and cools** and the water **condenses**.
* This cools the earth’s surface and warms the atmosphere

Layers of the Atmosphere (names & chart)

Thermosphere

v

Mesosphere

v

Stratosphere

v

Troposphere

Troposphere

* The unstable layer of the atmosphere: water and weather occurs here
* 75% of the total mass of the atmosphere
* The source of heat is Earth’s surface: this leads to the formation of clouds and storms
* Decreases density with elevation due to gravity

Stratosphere

* Location of the Ozone
* Temperature increases with increasing altitude: when UV radiation interacts with ozone molecules it increases radiation
* Stable: this is where planes fly

Mesosphere

* above stratosphere
* temperature decreases with height

Thermosphere

* above mesosphere (top)
* temperature increases with height

Tropopause

the “lid” of the troposphere

Pressure

the amount of force exerted per unit area

Pressure & Temperature

more pressure = more collisions = more **force** per unit area = higher **temperature**

Forces of Motion in the Ocean & Atmosphere (list)

1. Pressure: Pressure Gradient Force
2. Rotation: Coriolis Force
3. Gravity: Gravitational Force
4. Friction: Frictional Force

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the total acceleration of a particle is the total of all of these

* negative/positive forces work against each other to create the net change

Pressure Gradient Force

* movement will always want to go from a higher to lower pressure
* Pressure Gradient = difference between Pressure (P) over a distance (D)
* In the atmosphere, results in wind

Atmospheric Pressure Graph

What causes the speed of wind?

Pressure Gradient Force

* the more intense change in pressure, the faster winds will be
* it’s like being squeezed harder

Convergence

air moving towards the center of a pressure system

Divergence

air moving away from the center of a pressure system

Does air in a H pressure system converge or diverge?

diverge

Does air in an L pressure system converge or diverge?

converge

Mass Continuity (Conservation) - pressure systems

When a fluid is in motion, it must move in such a way that mass is conserved.

* if there is mass coming in, it needs to also have mass coming out, and vice versa

In terms of pressure systems, this conservation occurs via vertical movement

L and H pressure systems vertical/horizontal movements

L: convergence horizontally, divergence vertically

H: divergence horizontally, convergence horizontally

What type of weather is associated with L pressure systems? Why?

“inclement” weather: rain, storms, etc

* this is because convergence causes air to rise, and cool down in the process
* this creates condensation, causing cloud formation and precipitation

What type of weather is associated with H pressure systems? Why?

clear skies and sunny days

* as air horizontally diverges, vertical air needs to lower into the system to conserve mass
* descending air warms, and clouds disappear

Which holds more water vapor: warm or cool air?

* warm air: water can be absorbed
* cold air creates condensation since it can not hold the water, and forces it out

PGF at a small scale: Sea Breeze

Ocean has a higher specific heat than land, meaning that it doesn’t change temperature as quickly as land does

* as the land changes temperature, it creates a small-scale pressure gradient
* warm air rises from the land, so cold air from the ocean must travel to the shore, creating a breeze

Coriolis Force

a force that results from the Earth’s rotation

* deflects all “free moving” objects on earth (planes, missiles, water, etc.)
* __Northern Hemisphere__: deflects to the *right*
* __Southern Hemisphere__: deflects to the *left*