Activity

3.2
The Distribution of
Energy on Earth

Introduction: Solar Irradiance, the amount of energy reaching the earth, is a key factor in any study of Earth's climate. Since the 1960's scientists have used satellites to measure the intensity of incoming solar radiation as part of an attempt to unravel the questions behind Earth's energy budget. Earth's energy budget refers to the balance between incoming and outgoing radiation in the the Earth system. In a balanced system ENERGY IN = ENERGY OUT .  Current concerns about "global warming" have drawn increased attention to Earth's energy budget and solar irradiance measurements.  Since 1978 NASA has maintained records of satellite solar irradiance measurements taken by a variety of satellites.  In this investigationyou will explore satellite data to determine the distribution of energy arriving on the Earth's surface. Take notes on the Activity 3.2 Worksheet

PART I.  Understanding an irradiance data image.
 

Below is an image made from NASA satellite data.  The data for this image came from an instrument called ACRIM, which rides on the UARS satellite.  Learn more about ACRIMhere.  ACRIM collected data from 1983 to 1991. 
 

This image shows the distribution of energy arriving on Earth in the month of January.  When we measure the energy this way it is called Irradiance.  Scientists define irradiance as a measure of how much energy is flowing from the Sun over a particular area.  This satellite image is a picture of light energy flowing towards Earth.  Notice that some parts of the Earth are getting slightly less flowing energy per square meter (less dense) than other parts of the Earth.

Notice the color scale on the right of the image.  The scale tells the meaning of the colors on the image.  The units for Irradiance (swrad) are Watts per square meter (or W/m²)

Also notice the pattern (or distribution) of the energy.  Compare the energy at the equator with the middle latitudes, and with the high latitudes (far north and the far south).  Where is the energy measurement high?  Where is it low?  What are the measurements? (Compare the colors with the scale)

Part II  Getting data from the MAP Visualizer

Here is a Data Map Visualizer  The Visualizer can show you different kinds of data, for different months and years, for different parts of the world.  Open the Visualizer in another window and follow these directions:

1. On the Data Visualizer, select 

Parameter:  Surface Irradiance
Region: Americas
Year:  1984
Month: December

4.  Be sure to right click and save the scale also.  You only need to do that once... the scale will be the same for all Map Visualizer images.
 

Part III.  Analyze data and make inferences

1.  Create a webpage report on the following problem.  Write your hypothesis, then choose data from the Data Map Visualizer to test the pattern you think you will find.  You only need to choose 4 images. Which ones will you pick? 
 

2.  Link your completed webpage to your Web Portfolio page.

Copyright © 1999 Gallaudet University Laurent Clerc National Deaf Education Center All Rights Reserved Mon Jan 6 05:23:32 2003