1. Measuring Solar Aureoles with ADI Morton M. Sternheim www.umassk12.net/digital June, 2011

2. What is a Solar Aureole? It is a bright glow around the sun Caused by aerosols – suspensions of fine particles or liquid drops in the air Aerosols are usually dust, smoke, smog Aureole is larger when the concentration is higher Rain will tend to wash out aerosols ADI can quantify aureoles and provide air quality data

3. When Are Particulate Levels High? When the weather is calm, allowing pollution to build up. Around factories, during rush hour and near busy roads. When there is smoke in the air from wood stoves, fireplaces, forest fires or burning vegetation. Source http://www.mass.gov/dep/air/ aq/aq_pm.htm http://www.mass.gov/dep/air/ aq/aq_pm.htm

4. Sun and Sky Photography, Forrest Mims, http://www.sunandsky.org/Sky_Photos.html http://www.sunandsky.org/Sky_Photos.html Effect of Dust (Texas) Mexican smoke Sahara dust Clear sky Mauna Kea Summit Aureole No aureole Blue intensity

5. Particulates Can Cause Disease Asthma and chronic bronchitis Acute respiratory symptoms, such as coughing and chest tightness Decreased lung function, experienced as shortness of breath Heart attacks Premature death in people with heart or lung disease

6. Safely Photographing Aureoles Do NOT look directly at the sun; you can damage your eye Method 1. Use building roof or wall edge to mask sun Method 2. Use black ball or disk on rod, align camera with shadow (Mims)

7. Thursday, Sept 16, 2010 (before rain) Friday, Sept. 17, 2010 (after rain)

8. Analyzing With ADI Open picture Spatial analysis (button)  Select Spatial Tool  Line Tool Click and drag a line across the areole File  Draw color across line

9. Thursday, September 16, before rain

10. Friday, Sept. 17, 2010 (after rain)

11. Observations The aureole is smaller after rain has washed out aerosols In the second (after the rain graph), relative to the blue component, there is a much steeper drop off in intensity for the red and to some extent the green component. (The red peak is much sharper). Longer wave length light (red) scatters mainly from the larger particles in the atmosphere, and the rain has washed out much of this material. (If there are no aerosols, there is no aureole, and you just get a blue sky - the blue intensity plot is almost flat as you go away from the sun.)

12. Coronas Colorful halos around the sun (or moon) Generally due to ice crystals or water droplets; sometimes pollen Corona due to juniper pollen in Texas (Mims)

13. Technical details Try to take the photos from the same location and about the same time each day. I took mine near noon. The same zoom is also desirable. You will need a size scale for detailed comparisons. Select an object or building feature and assign it an arbitrary size. Use the same object and size in analyzing each photo.

14. Air Quality Data EPA AIRNOW – particulates, ozone http://www.airnow.gov/ http://www.airnow.gov/ Massachusetts Department of Air Quality http://www.mass.gov/dep/air/airquali.htm http://www.mass.gov/dep/air/airquali.htm

15. Some Research Questions How do the ADI measurements correlate with reported Particulate Matter levels? What happens when it is very dusty, perhaps from winds blowing across recently plowed fields? Can you see the effects of pollen? Can you see the effects of dust from an Icelandic volcano coming around the globe to here? What does the aureole look like after a hurricane or northeaster? Will classes in urban and rural areas get the same results at a given time?

16. References How to Analyze Digital Images, Forrest Mims, The Citizen Scientist How to Analyze Digital Images, Forrest Mims, The Citizen Scientist Sun and Sky Photography, Forrest Mims, http://www.sunandsky.org/Sky_Photos.html http://www.sunandsky.org/Sky_Photos.html David R. Brooks, March 2008, Photographing the Solar Aureole: A Different Way of Looking at Particulates and Scattered Light in the Atmosphere http://www.instesre.org/Solar/AureolePhotography/A ureole.htm http://www.instesre.org/Solar/AureolePhotography/A ureole.htm