1. Solar Radiation: The driving factor Radiative Energy (energy transmitted as waves, rays and particles) released, absorbed & reflected by all things travels as both a particle and a wave is affected by - - gravity, magnetism, and atmosphere composition, distance, angle of incidence provides Earth with an external source of energy - EXOSPHERE

2. The sun produces most of its electromagnetic energy in intermediate wavelengths / frequencies. A.True B.False

3. Sources of radiation Sun and other stars are dominant source -Sun is closest so it has a greater influence Earth emits some energy as well -Solar radiation is absorbed by Earth and transformed into longwave radiation Many other planets emit radiation as well -e.g., Jupiter and Saturn -source is from the planet itself not all is absorbed and re-emitted like Earth

4. The Sun 93 million miles from Earth It rotates once every 600 hrs (25 days) Has hot spots and "cool" spots -sunspots are relatively "cool" Produces electro- magnetic radiative energy -concentrated in UV, Visible & IR spectral classes

5. Energy output from the sun Variable Changes with time Changes over long term - billions of years short term – 11 year cycles The earth receives a small percentage of the total output of energy from the sun Energy output from the sun Variable Changes with time Changes over long term - billions of years short term – 11 year cycles The earth receives a small percentage of the total output of energy from the sun

6. Sunspots - cyclical magnetic “storms” that occur in 11 year cycles are lower in temperature, but increase solar output. Solar Max = lots of sunspots and increased energy output Solar Min = few to no sunspots and decreased energy output

7. Frequency (mHz) refers to vibration of particles Wavelength ( ) = distance between wave crests Electromagnetic Spectrum Long Short ((

8. Position affects amount radiation we receive Far away=less radiation Titled toward= more radiation Far away=less radiation; Closer=more radiation Titled away=less radiation; Tilted toward = more aphelion perihelion

9. Our seasons on Earth are NOT related to distance from the Sun Earth is at Aphelion during the northern hemisphere summer months (our warm months) “Aphelion” means farthest away from the Sun farther away means less energy reaches the surface but that change is very small compared to those related to tilt Earth’s seasons are due to the tilt of our axis of rotation! changes the length of the day; and changes the angle of incidence for incoming solar energy

11. The northern hemisphere experiences winter because the Earth is farther away from the Sun than it is during the summer months. A.True B.False

12. Milankovitch Orbital Variations Eccentricity – orbit around the Sun changes from a circle to an ellipse over a 100,000 year cycle Obliquity-Earth’s axis of rotation changes from 22.5 to 24.5°over a 41,000 year cycle Precession of equinox- earth wobbles very slowly as it spins, changing the timing of seasons with respect to perihelion and aphelion 22 to 25 kyr All three are independent of one another. Change in energy reaching the Earth is small and requires amplification by Earth systems to initiate climate change

13. Eccentricity 100 kyr cycle aphelion Earth’s orbit

14. Obliquity 41 kyr cycle Perpendicular to the ecliptic Axis 20 kyr ago Axis at present Axis at 20 kyr in future

15. Conditions now Conditions 11 kyr ago Precession of Equinox 22-25 kyr cycle sun Earth at aphelion Earth at perihelion Path of Earth’s orbit around the sun

16. Precession 22 -25 kyr cycle

17. Milankovitch cycles- pacemaker to the ice ages  from  O 18 ice and deep sea sediment cores *

18. The atmosphere acts as a mirror, prism and a trap Scatters some of the radiation -why the sky is blue Reflects some of the radiation -clouds, snow, water etc. Absorbs some of the radiation -ground, ozone, dust, etc. Ozone & dust Dust & clouds Clouds & gases mirror prism trap

20. Albedo ･ A measure of the amount of reflected radiation ･ Some things reflect radiation better than others -"dry" or "cold" Snow & Ice = high albedo -water = moderate for visible, low for infrared -plants= moderate for visible ･ Land absorbs and releases radiative energy quicker than water Albedo = ________________ incident radiation reflected radiation

21. Albedo of land surfaces on Earth Data collected by NASA’s MODIS satellite, April 2002 Warm colors are higher; cool are lower; white no data available

22. IR output from Earth K

23. Effects of cloud type on radiation budget different types of interference have different effects on Earth's energy budget