1. Insolation and the Greenhouse Effect Energy in Earth’s Atmosphere

3. Insolation: Incoming Solar Radiation The Sun’s strength or intensity depends on three factors: 1. Angle of insolation 2. Duration of insolation 3. Type of surface it strikes

4. Angle of Insolation

6. Where are we and how much are we getting right now? Autumnal equinox Fall in the northern hemisphere Winter solstice Winter in the northern hemisphere

7. Vernal Equinox Spring in the northern hemisphere Summer solstice Summer in the northern hemisphere

8. Duration of Insolation Length of time the sun is up. Relationship: longer duration of insolation, higher the temperature (more intense) Varies with latitude

9. Absorption of Insolation Only 50% of the sun’s energy is absorbed by Earth’s surface. Rest is reflected, scattered or absorbed by the atmosphere. The absorption of heat energy from the sun depends on the specific heat of the substance. Land has a lower specific heat, so takes less time to heat up, while water has a higher specific heat, thus taking more time to heat up.

10. Four Reasons water and land temperature differ: Water has a higher specific heat. Water reflects low angle insolation better. Water is transparent  insolation penetrates more deeply, more quickly. Convection currents carry heat energy into hydrosphere  land heats faster than water and land cools faster than water. GOOD ABSORBERS ARE GOOD RADIATORS

11. Color or structure of surface also determines if heat will be absorbed or reflected In general, light colored surfaces reflect While dark colored surfaces absorb Incoming energy from the sun: UV, visible and infrared Outgoing energy from Earth: terrestrial radiation – infrared.

12. INSOLATION WRAP-UP Angle of insolation = how high sun is in sky. Measured from the horizon (position of the sun)  greatest angle = 90 ⁰ Changes with the seasons – in Northern Hemisphere: Lowest noontime angle =December 21, winter solstice Highest angle =June 21, summer solstice As angle of insolation increases and duration of insolation increases- temperature increases. Most energy gets to Earth’s surface as visible light. Ozone absorbs high energy radiation Infrared radiation is absorbed by water and carbon dioxide. A substances reflectivity = albedo

13. Insolation – Temperature Lag A time lag exists between time of greatest intensity and time of highest air temperature. WHY? Ex: June at noon – Earth receives most solar energy but highest temperature is later. Because temperature depends on the balance between incoming energy and energy lost. Even after maximum insolation, Earth continues to receive more energy than lost  temperature continues to rise during this ‘lag’ period. Following balance, energy lost > energy gained therefore about mid afternoon temperature drops.

14. What is the Greenhouse Effect? http://earthguide.ucsd.edu/ea rthguide/diagrams/greenhous e/ http://earthguide.ucsd.edu/ea rthguide/diagrams/greenhous e/ Natural effect Keeps our planet inhabitable Other greenhouse planets- Venus

15. Comparing the Earth to a greenhouse The glass=the earth’s atmosphere Inside the greenhouse=conditions here on earth’s surface Which type of ray is incoming? Which type of ray is outgoing?

16. Terrestrial Radiation The form of energy the earth gives off Infrared=outgoing Visible light=incoming

17. Greenhouse gases

19. What is global warming the result of? Addition of more greenhouse gases to the atmosphere Greenhouse gases are added naturally and by human activities

20. What are the effects of global warming? Warmer temperatures globally Melting of polar ice cap and glaciers Sea level rise Climate change More severe weather?

21. What can you do? Lower your energy consumption (burning of fossil fuels) Recycle Lower your carbon footprint