Homework Assignment – Good job!

I was very happy to see a great response.

As of mid evening yesterday I had over 110 e-mails - but there are only 61 people in the class!

Today

Quick review

Introduction to the electromagnetic spectrum

First in-class activity – Ecological Footprint

Last ClassUnderstanding global change is understanding howthe earth system functions.

This requires information from many disciplines and

Consideration of different time scales, ecosystem typesAnd human interactions

Over the last 150 years humans have- experienced a tremendous increase in population- altered much of the land surface- altered atmospheric greenhouse gas concentrations

Over the last 150 years- temperatures have increased- rainfall patterns have changed

1995 1997

Brazilian Rainforest Loss in Two Years

We are orbiting one ofMany stars in many Galaxies

We locate everything inSpace based on the typesof radiation or light itgives off.

The various wavelengthsare called the electromagneticspectrum.

This is our sun, a nicemid-sized, middle agedStar.

It’s about 5 billion yearsOld, and has another 5Billion or so years left.

The energy that this starGives off, modified andtempered by our atmosphereAllows life to exist here,So we can worry about globalChange.

All wavelengths travel at the speed of light, so if the wavelength is shorter, it must have a higher frequency.

Listen to the radio or watch tv,Talk on a cb or…

Learn what objects in space areMade of

Heat your popcorn study galaxies

Keep your food warm in your fastFood restaurant or

See this lecture!

Get a tan or maybe go extinct!

Find out if your bone is broken

Released from some radioactive elements

Everything emitsElectromagneticRadiation

Some general rules about EM radiation

The type and amount of radiation emitted depends on the temperature of the object.

The hotter the object the more radiation is emitted. (Our hot Sun emits lots of radiation/ light).

Also, the hotter the object, themore energetic the radiation.

Planck’s Law

Looks a bit scary, but it isn’tReally that bad.

The amount of energy releasedBy an object at any temperatureIs higher an shorter wavelengths

Wein’s Law

Not nearly as scary, but just as important

The most common wavelengths an objectemits are inversely related to Temperature.

Sefan-Boltzmann Law

Is the simplest formula yet

The amount of energy emitted by anobject is increases with temperature.

Our sun is really hot and emits most of it’s energy at shorter wavelengths. Good thing for us if we want to see, but not so good if we didn’t have an atmosphere.

What does all this mean to us?

So just why is the atmosphere so important?

The Doppler effect

If an object is approaching us,The wavelengths appear to be getting shorter

If an object is moving away fromUs, the wavelengths appear to be Getting longer.

Think of the sound of a train whistle as the train approaches and then Moves away.

Worldwide, the biologically productive space available per person is 2.2 hectares or 5.4 acres.

- part of the land surface and part of the ocean

- most deserts, polar regions, and cities excluded

Calculating one persons impact on the earth

http://www.mec.ca/Apps/ecoCalc/ecoCalc.jsp?FOLDER%3C%3Efolder_id=65723

Electromagnetic Spectrum – Web site for Review

http://imagine.gsfc.nasa.gov/docs/science/know_l1/emspectrum.html

Doppler effect

http://webphysics.davidson.edu/Applets/Doppler/Doppler.html

Class Assignment: Ecological Footprint