1. Physics of Planetary Climate Cors221: Physics in Everyday Life Fall 2010 Module 3 Lecture 1: Science and Light

2. What is Climate? Climate is what you expect; weather is what you get. -- Robert Heinlein Climate: composite or generally prevailing weather conditions of a region, as temperature, air pressure, humidity, precipitation, sunshine, cloudiness, and winds, throughout the year, averaged over a series of years

3. Climates of Earth Climate of Moscow, Idaho

4. The Scientific Method Observation Hypothesis Prediction Experiment Science can not prove a positive; It can only disprove, or prove a negative

5. #1 Driver of Climate: Sunlight In order to understand Earth's heating, need to understand light first.

6. What is light? Light is the propagation of an electromagnetic disturbance – an electromagnetic wave.

8. Blackbody Radiation Lava from Kilauea in Hawaii; molten rock has a temperature of around 1000 K – the minimum for visible glowing is 800K.

9. Blackbody Radiation: Wien's law Wien's law: wavelength b=3000 for T in Kelvin; lambda-max is in microns

10. Blackbody Radiation

11. Total radiated energy, in Watts per square meter, is proportional to the temperature to the 4 th power!

12. Can you measure a person's blackbody emissions? A camera for light at 10-microns wavelength

13. Sweet! What else can you do with tishth ing? 10-micron image

14. Sweet! What else can you do with tishth ing? 10-micron image

15. Sweet! What else can you do with tishth ing? 10-micron image

16. Sweet! What else can you do with tishth ing? 10-micron image

17. Summary ✔ Science can only disprove, not prove ✔ Climate is what you expect; weather is what you get ✔ Light, all light from radio to gamma rays, is electromagnetic radiation ✔ Shorter, bluer wavelengths have more energy and are more dangerous than longer, redder wavelengths. ✔ All bodies emit blackbody radiation; hotter bodies emit more ( T 4 ) light and bluer (shorter wavelength) light. ✔ Earth cools by radiating infrared light to space by blackbody radiation