Solar Radiation: The driving factor Radiation (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

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

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

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

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

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

Position affects radiation Far away=less radiation Titled toward= more radiation Far away=less radiation; Closer=more radiation Titled away=less radiation; Tilted toward = more

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

Eccentricity 100 kyr cycle aphelion Earth’s orbit

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

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

Precession 22 kyr cycle

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

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

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

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

IR output from Earth K

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