CLIMATE

After the surface of the earth cooled and surface crust (lithosphere) formed, the planet surface took on something of the “look” it has today – land, air, oceans (lithosphere, atmosphere, hydrosphere)

The temperature at the ______ of the earth is determined, not by geology of the core but primarily by energy coming from outside – the _____.

NASA

What is energy?

The capacity to do work (move mass) and transfer heat

Two main forms: 1. ________ – a mass moving 2. _________ – “stored” in a structure, molecule, nucleus - able to become kinetic under right conditions

Where does the sun get it’s energy? Nuclear fusion

Atoms of hydrogen fuse to form __________ – releases large amounts of energy

Requires extremely high pressure & temperature conditions, such as exist in the sun. Fusion reactions further _______ these temperatures.

9-18/10-19

Nuclear fusion

FuelProton Neutron

Hydrogen-2(deuterium nucleus)

Hydrogen-3(tritium nucleus)

Reactionconditions

100million °C

Products

Helium-4 nucleus

Energy

Neutron

How does the sun supply energy to the earth?

The sun is a “hot body”. Hot bodies emit ___________ waves (EM), as a function of their temperature.

What are electromagnetic waves? Light.

Physicists tell us that light has both ____ and particle properties. The particles are called “photons”, the wavelength measures their energy level.

The energy of light is determined by ___________ 

hc E = energy E = ------ h = Planck’s constant

c = speed of light = wavelength

Shorter waves = _______ energy

There is a broad spectrum of wavelengths and energies

Visible light is a small segment of the electromagnetic spectrum

The sun emits electromagnetic waves as a function of its temperature. Its heat results from nuclear fusion (H to He) Peak (intensity) wavelength of a radiating body (Wein’s law) Max = 2.88 x 106 / T (oK) T = temp Sun temperature 5750 oK Sun’s max = (2.88 x 106)/5750

= 500 nm (__________) 

Interestingly, at planet formation, sun 25% ________; max = 670nm – orange

Stars heat up as they age (why?)

0

200

400

600

800

1000

1200

3000 4000 5000 6000 7000

Temperature (K)

Pea

k W

avel

eng

th

Total light energy is distributed around this peak wavelength

2-6

Much of the energy hitting the earth is in the ______ spectrum

Is this just a lucky coincidence?

“Solar _________” = 2 cal/cm2/min1 cal/cm2/min reaches surface

The density (#photons/m2) _________ with distance from the sun

The energy density intercepted by the earth is determined by the distance to the sun.

Varies through the year – orbit an _________.

The total energy intercepted by the earth a function of area of the “profile”.

This energy input creates a surface temperature, a “dynamic equilibrium” – a balance of inputs and outputs

(earth radius = 6378km)

2-10

Solar constant x area =

2.495 x 1018 cal/min

What is a dynamic equilibrium?

“Equilibrium” describes an entity that appears _____________ over time, a “steady state”.

For example, a tub of water half full.

There are at least two ways that tub could stay half full.1. Turn off the tap - it sits there unchanging.2. Leave the tap on, but open the drain.

#2 is a “dynamic equilibrium”

Obviously, a key relationship for a dynamic equilibrium is

________ = __________

What happens to an equilibrium if you increase inputs?Does the water level go up, down, stay the same?

What did you assume to decide on your answer?

We can easily imagine at least three ways to get a dynamic equilibrium in our bathtub

1. ________ output, ________ input – adjust input to match output. Total amount in tub is irrelevant. (could also have fixed input, match output)

2. Output __________ as input increases.a. tub is fixed size, overflow = input, tub full.b. output increases as amount in tub increases, output eventually matches input

What kind of dynamic equilibrium is earth surface temperature?

Surface temperature is a balance of solar inputs, reflectance, _________ and re-radiation (into space).

Type 2b dynamic equilibrium

As the earth heats up, it re-radiates more (output increases)

If no re-radiation, no heat loss, earth ____________.

Higher input, _________ equilibrium temperature.

Re-radiation is also EM waves, at _____ wavelength

If sun was cooler in past, earth was __________, yes?

Maybe, but this ignores the “greenhouse effect”

Components of atmosphere absorb outgoing wavelengths, re-radiate back to _____, increase heat before leaving at lower energy.

Depends on composition of the atmosphere.

Carbon dioxide, ________, __________, and nitrous oxide are strong “greenhouse gases”. Early earth atmosphere was _____ in these, so may have been as warm as or warmer than today (est. 23oC).

Question: what would be an equivalent of the greenhouse effect in the bathtub analogy?

Barry Saltzman, Dynamical Paleoclimatology: Generalized Theory of Global Climate Change, Academic Press, New York, 2002, fig. 1-3.

Estimates of global temperature indicate lots of changes during the history of the planet.

Including “_________” that lasted many thousands of years

                                                                                                               

                                    Much of the earth was covered with ice packs miles deep, that altered the landscape and created lakes and rivers when they melted.

NOAA

The most recent glacial period began about 70,000 years ago, and ended about _________ years ago.

These changes in ice pack directly affect the amount of liquid water and therefore ocean levels.

12-16/12-15

12-17/12-16Greenhouse gas composition is one factor affecting this temperature variation

12-17/12-16

Dynamical systems like surface temperature can be difficult to understand and predict because of the interconnectedness of the component processes.

These connections create feedback loops, or causal cycles rather than simple causal chains like A affects B affects C.

For example, two simple feedbacks

1. ________ feedback – increase in A increases B, which decreases A. “homeostatic”, “stable”

2. _________ feedback – increase in A increases B, which further increases A. “Blowup” or “collapse”.

A B

A B

+

+

+

_

In earth temperature regulation, we have already seen an example of each

1. Re-radiation: _________ feedback. Increasing solar input (heating) results in increased radiation to space (cooling)

2. Water Vapor: __________ feedback. Increased temperature increases evaporation, increased water vapor in atmosphere increases greenhouse effect.

Earth temp. Re-radiation

Earth temp.

Water vapor

+

+

+

_

But also, increased water vapor in the atmosphere tends to increase cloud cover, which increases ________ and thereby decreases earth temperature

Earth temp.

Water vapor+

+

Cloud cover

+_

What would you call this??

Predicting cloud cover is an important source of _________ in climate modeling.

In the bathtub analogy, what is equivalent to cloud cover?

Solar energy density is not even across the earth or through the year – climate varies from place to place.

_____ in winter, _____ at poles.

Opposite seasons in the northern and southern hemispheres

Three basic ways heat is transferred:1. Convection – movement of heated fluid due to density2. Conduction – direct contact – molecular collisions3. Radiation – EM waves from hot body

_________ cells – warm moist air rises at equator, cools, rains; high dry air moves toward poles, cools and sinks.

Wind and ocean currents move heat around

12-3

Six “Hadley cells” in earth redistribute heat and moisture

Wind and ocean currents move heat around

_____ winds form due to earth’s rotation – faster at equator than at poles

Which way does the earth turn?

Similar forces generate ocean currents: differences in temperature, wind, topography, _______, earth’s rotation

Wind and ocean currents move heat around

http://earth.usc.edu/~stott/Catalina/Oceans.html

These currents can alter ________ on land in coastal areas

Cold, salty water in the North Atlantic sinks and flows south into the Pacific, eventually warms, rises and returns.

Topography can also alter climate 1. High altitude air is ________

– lower pressure 2. The “rain shadow effect”

– ______ on the “lee” side

Weather – large air masses generally moving and interacting – local climate conditions frequently change

Fronts – where different air masses contact, energy is transferred.

______ front – moving warm air mass contacts a cold mass, it rises up, widespread clouds.

______ front – moving cold mass drives under a warm air mass, sudden cooling, strong winds and rain.

Tornadoes

Hurricanes (Typhoons)

High energy concentration can result in special storms with spiraling high velocity winds

___________ cycle

2-19/2-25

_____ driven evaporation of water into air begins a cycle as the warm moist air rises, condenses to clouds and rain, which returns directly to surface water (lakes, oceans) via rivers and underground (ground water flow), and so on.

Energy flow and material cycles

The water cycle is an example of a general natural pattern on earththe linkage of the flow of energy and cycling of materials

Liquid Water

Water vapor

EM (Solar)

EM (Space)

Energy flows Water

cycles

12-2

These multiple forces drive variation in climate across the world

NOAA

Conclusionsearth a dynamic process, has historygeologically active – rock cycletemperature a balance of factorssolar energy drives climate patternswater cycles through its statesflows of energy and cycles of materialsinteraction of geological and solar energy