Insolation

• Insolation: the amount of solar energy received by a region of the Earth's surface

  • short for incoming solar radiation
  • the sun is the source of almost all energy on Earth
• Insolation is affected by:

  • time of year
  • angle of inclination
  • length of daylight
  • cloud cover
  • Albedo effect
  • atmospheric dust
• Angle if inclination is he degree that the Earth's poles are tilted from the plane of orbit

  • affects the angle of incidence
  • 23.5 degrees

  
• Angle of incidence is the angle between the ray falling on the surface and the line to that surface

  • increases as you move from the equator to the poles due to the curvature of the Earth
  • high angle of incidence = solar energy is spread out and the area receives less year-round insolation
• Seasonal changes are the results of the Earth's angle of inclination and the changes of the angle of incidence

  • summer solstice in the NH the angle of inclination causes the North pole to be tilted toward the sun
  • decreased angle of incidence and greater insolation and more hours of daylight during the summer
• • When it is summer in the Northern Hemisphere = winter in the Southern Hemisphere.
  • When it is winter in the Northern Hemisphere = summer in the Southern Hemisphere
• Latitudes near the equator experience little seasonal variation in the amount of insolation and hours of daylight
• Albedo Effect is the percentage of solar radiation that it reflects

  • light-coloured, shiny surfaces reflect more that darker, duller surfaces (snow & ice > forests & water)
  • thus, albedo varies with the season
  • average albedo os the Earth is 30%
  • 30% of solar radiation that falls on the Earth is reflected back into space
  • each region has a different albedo value
• Cloud cover reflects incoming solar radiation

  • thus, lower air temperature on a cloudy day
• Atmospheric dust reflects incoming solar radiation

  • reduces the amount of solar energy that reaches the lithosphere and hydrosphere