ATM OCN (Meteorology) 100

ATMOSPHERIC ENERGETICS (continued):

PART II: RADIATION

Summer 2001

Lecture # 4 scheduled for:

21 JUN 2000 (R)

Today's Lecture Objectives:

To identify the electromagnetic spectrum and to describe how the various forms of electromagnetic radiation differ from one another.
To state in your own words the basic electromagnetic radiation laws describing the amount and spectral character of the emitted radiation.
To distinguish between solar radiation and the radiation emitted by the earth-atmosphere system.
To distinguish between scattering, reflection, absorption and transmission.
To explain how the radiant flux emitted from a point source diminishes with the inverse square of the distance and evaluate the variation of flux for various planets at known distances from the sun.
To give a suitable definition for the solar constant and provide a currently accepted value of the solar constant.
To describe the basic motions of the earth in space, explaining the existence of the diurnal and seasonal cycles and identifying the approximate dates of the solstices, the equinoxes, perihelion and aphelion.
To sketch the key features of the solar illumination geometry (in terms of solar altitude and daylight length) for various locations on earth at the solstices and equinoxes.
To explain how solar altitude influences the intensity of solar radiation received at the earth's surface.
To define albedo, explain its significance and list the factors that cause variations in the albedo of an object.
To explain why the atmosphere is heated chiefly by terrestrial radiation.
To explain the atmospheric effect ("greenhouse effect") and identify the gases chiefly responsible for this effect.
To summarize the cause and possible effects of stratospheric ozone depletion.

Outline:

NOTE: This lecture is continued from Atmospheric Energetics - Part I: Heat, Energy & Energy Transport

A. INTRODUCTION

B. RADIANT ENERGY or ELECTROMAGNETIC RADIATION

The nature of electromagnetic radiation

Wave forms
Terminology describing waves
The electromagnetic spectrum

Important relationships of radiation

Ideal radiators/absorbers ("black bodies")
The ideal radiator curve
Total amount of energy emitted/absorbed
Region of maximum radiation
Inverse-square relationship
Angle of incident radiation ("cosine law")

C. THE EARTH, THE SUN and THE RADIATION LINK

The Sun and Solar radiation
Our place in the sun -- Annual and diurnal motions of Planet Earth
Disposition of solar radiation in the Earth-atmosphere
Albedo

Definition
Implications

Terrestrial radiation

Continues in next lecture as Atmospheric Energetics - Part III: Energy Budgets

Links to Other References:

Additional information can be found on the Internet through the following sites:

Today's Space Weather from Space Environment Center
A Primer on the Space Environment Our Star, the Sun from Space Environment Center
Solar images from the Space Environment Center
Information on the sun, radio and space services
For K-12 Educational Resource Links

About the Sun from the NCAR High Altitude Observatory
Education and Outreach links from Space Environment Center

Here Comes the Sun: A Solar/Terrestrial Tutorial from Plymouth State College.

Last revision 4 June 2001 (0220 UTC)

Produced by Edward J. Hopkins, Ph.D.

Department of Atmospheric and Oceanic Sciences

University of Wisconsin-Madison Madison, WI 53706

hopkins@meteor.wisc.edu

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