Follow the EnergyFollow the Energy

Adapted from Scott Denning’s presentation for the CSU CMMAP course Summer 2007

By Jim Barnaby Summer 2008

Follow the EnergyFollow the EnergyAn Overview of Energy’s An Overview of Energy’s

Effect on the Earth SystemEffect on the Earth System

What is energy?

Potential & Kinetic Energy

Types of Energy

Conservation of Energy

Energy flows downhill from hot to cold

Effect of Energy on Matter (Molecular Motion)

Law of Conservation of Energy

What is Energy?What is Energy?

• What is Energy?

My 8th grade textbook says, “Energy is not matter”

Matter is anything with mass & volume

Can we change matter into energy?

How?

Many textbooks now say:

Matter is Frozen Energy

Energy Can Come From ReactionsEnergy Can Come From Reactions

Mass can be converted into energy in nuclear fission and fusion reactions. Fission and fusion involve atomic nuclei and release tremendous amounts of energy.

Einstein showed that if matter is destroyed, energy is created and if energy is destroyed, matter is created. The total amount of mass and energy is conserved.

Defining Energy is HardDefining Energy is Hard

“Energy is the ability to do work”“Energy is the ability of something to cause change”

(Physicists define work as “when force moves an object”)

All work requires energy

Work and energy are the same thing

Energy is CurrencyEnergy is Currency

Energy is the universal currency of life

—it causes change and makes things happen

““Energy Changes Energy Changes Make Things HappenMake Things Happen””

• Energy is a property or characteristic of matter that makes things happen, or, in the case of stored or potential energy, has the "potential" to make things happen.

• Without energy, nothing would ever change, nothing would ever happen. You might say energy is the ultimate agent of change, the queen mother of all change agents.

Dave Watson, http://www.ftexploring.com

Copyright 2000-2007. The Flying Turtle Company. All rights reserved

Kinetic Energy moves meKinetic Energy moves me

Kinetic Energy (KE)Energy in the form of motion

Depends on mass and velocity of moving object.

  Object in motion has ability to do work.

“… “… They Said I had Potential”They Said I had Potential”

Potential Energy (PE)Stored energy due to position

 Examples: rock on a cliff, battery, food, gasoline, stretched rubber band, apple growing on a tree

 

Work is done on object to gain PE

Types of EnergyTypes of Energy

Five forms of energy:

Mechanical

Heat

Chemical

Electromagnetic

Nuclear

Conservation of EnergyConservation of Energy

• Energy can be stored

• Energy can move from one piece of matter to another piece of matter

• Energy can be transformed from one type of energy to another type of energy

• The First Law of Thermodynamics:– During all this moving and transforming the total amount of energy never changes.

Kinds of EnergyKinds of Energy• Radiant Energy -- light

• Kinetic Energy -- motion

• Gravitational Potential Energy -- height

• “Internal Energy”– Temperature, Pressure -- hot air– Chemical energy– Nuclear energy

• Conversions among different kinds of energy power all that happens in the weather and climate!

If Energy is Conserved …If Energy is Conserved …then why do we need to “conserve then why do we need to “conserve

energy?”energy?”• Total energy is conserved (First Law), but not its usefulness!

• Second Law of Thermodynamics: Energy flows “downhill” from highly concentrated (hot) forms to very dilute (cold) forms

• Gasoline burned in your car (hot) makes it move

• Turbulence and friction of tires on road dissipated as heat

• Heat radiated to space (cold)

Energy Energy Makes Makes Things Things HappenHappen

Hurricane Katrina Devastation in Biloxi, Mississippi Hurricane Katrina Devastation in Biloxi, Mississippi August 29, 2005August 29, 2005

Energy’s Effect on MoleculesEnergy’s Effect on Molecules

How does heat energy effect atoms and molecules within matter?

Heat energy (hot) speeds up molecular motion

Lack of heat energy (cold) slows down molecular motion

Everything obeys this lawEverything obeys this law

The law of Conservation of Energy:  Energy cannot be created or destroyed. It may be transformed from one form into another; however, the total amount of energy in the universe remains constant. (Transformers)

 

Energy conversions occur without a gain or loss in energy

 Due to friction, energy might seem to be lost, but it has changed into thermal energy. 

It all Starts with the SunIt all Starts with the Sun• Nuclear fusion in the Sun powers all changes on the Earth!

• Solar energy heats the air, lifts it, blows it around, evaporates water, makes snowstorms

• Conversion of solar energy and downhill dissipation as heat energy drive all weather and climate phenomena

• Energy comes in hot, and goes out cold

Planetary Energy BalancePlanetary Energy Balance

Energy In = Energy Out

What’s Missing?What’s Missing?

• Vertical structureThe “greenhouse effect”

• Energy storage and transportThe “general circulation” of the atmosphere and oceans

Vertical Structure is CrucialVertical Structure is Crucial

• The world is a big place, but the atmosphere is very thin, and most of it is close to the ground– About 15% of the atmosphere is below our feet

– At the top of Long’s Peak, the figure is 40%

– You are closer to outer space than you are to Colorado Springs!

• Changes in atmospheric temperature with height are responsible for the “Greenhouse Effect,” which keeps us from freezing to death

Vertical Thermal StructureVertical Thermal Structure

• Heated from below by latent and sensible heat fluxes

• Heated in stratosphere by ozone absorption

The Job of the AtmosphereThe Job of the Atmosphereis to let the energy out!is to let the energy out!

“Piles up” in tropics “Escapes” near poles and aloft

The movement of the air (and oceans) allows energy to be transported to its “escape zones!”

Energy Reservoirs (Stored Energy Reservoirs (Stored Energy)Energy)

• The oceans are about 4,000 m (12,000 ft) deep

• The top 10 m (30 ft) equal the mass of the atmosphere

• The top 3 m (9 ft) equal the heat capacity of the atmosphere!

AtmosphereOcean

The state of the oceans determines the climateon time scales of thousands to millions of years!