Unit 2: Abiotic Factors

• Nature of solar energy

  • Comes to Earth as photons (particles of light energy) of electromagnetic waves
  • Energy of a photon is inversely proportional to its wavelength
• SOLAR ENERGY THAT REACHES THE EARTH

  • 4% ultra violet

  • 44% visible light

  • 52% infrared and long waves
• • higher energy wavelengths are screened out by upper atmosphere
  • much infrared radiation is screened out by water and carbon dioxide before reaching earth’s surface
• EARTH AND THE SUN’S RAYS

  • Radiation received by a given surface is either

  • Absorbed

  • Transmitted

  • Reflected by the surface
• Albedo – describe reflectivity of the surface
• 30 units of energy reaching the earth’s surface is reflected back into space

  • 25 units by atmosphere

  • 5 units by Earth’s surface
• • 70 units are absorbed

  • 25 units – atmosphere and clouds

  • 45 units – Earth’s surface

  • Absorbed radiation is used to

  • Heat the atmosphere and the Earth’s surface

  • Evaporate and cycle water

  • Generate winds

  • 0.023 units – captured by green plants and autotrophs

  • Converted to chemical energy by photosynthesis

  • Drives all life processes on Earth
• • visible light – most of the solar energy reaching earth to which the atmosphere is transparent
  • infrared radiation (heat energy) – most energy re-emitted
  • greenhouse gases – influence rate at which heat flows through the atmosphere and is released to space
• GREENHOUSE EFFECT – ABSORPTION OF THE LONG WAVE

  RADIATION BY THE ATMOSPHERE AND ITS EMISSION BACK

  TOWARD EARTH
• Weather

  • day-to-day manifestations of the troposphere’s properties
  • created by the movement wind air masses
  • maintained by the flow of solar energy
• Climate

  • average long-term pattern of weather in a particular area
  • defined by year-after-year patterns of temperature and precipitation
• Climate – what we expect

  Weather – what we get
• WHAT DETERMINES GLOBAL CLIMATE PATTERNS?

  1. The Sun's rays and the spherical earth
  2. Elliptical orbit and to the earth's rotation around the sun
  3. Global tilt and the Earth's axis
  4. Atmospheric circulation
  5. Placement of continents and oceans
  6. Ocean currents
• 2. Elliptical orbit and the Earth’s rotation around the Sun

  Earth rotates at the rate of 365.25 days/revolution

  • ellipse – orbit

  Perihelion – Earth is nearest the sun (January 3)

  Aphelion – farthest from the sun (July 4)
• 3. Global tilt and the Earth’s axis tilted at an angle of 23.50 leads to uneven heating of the earth

  • produces seasons and climate patterns

  Poles – no sunlight during much of winter

  Tropical region – almost uniform amount of solar energy

  Temperate region – experience four distinct seasons
• Winter solstice is the

  • shortest day of the year
  • occurs on December 21 and marks the beginning of winter

  Summer solstice is the

  • longest day of the year
  • occurs on June 21 and marks the beginning of summer
• EQUINOX

  • Equinox literally means "equal night“
  • A day lasts 12 hours and a night lasts 12 hours at all latitudes

  Vernal (spring) equinox occurs March 21.

  Autumnal (fall) equinox occurs September 21
• Coriolis effect – causes deflection of moving objects to the right in the Northern Hemisphere and to the left in the Southern Hemisphere due to the earth's rotation
• 4. Atmospheric circulation

  • Descending dry air absorbs moisture.
  • Ascending moist air releases moisture.
• Ocean currents plays a major role in distributing heat helps mix ocean waters and redistribute nutrients needed by aquatic organisms

  Ocean currents plays a major role in distributing heathelps mix ocean waters and redistribute nutrients needed by aquatic organismsed by aquatic organisms

  • upwelling – vertical changes
• Microclimate - determines the conditions for survival of most organisms

  Vegetation – moderates the climate of a given area by altering wind movement, evaporation, moisture and soil temperature

  Urban microclimate – product of the morphology of the city and the density and activity of its occupants
• Soil is created by

  1)Weathering of rock

  2)Deposit of sediments by erosion

  3)Decomposition of organic matter in dead plants and animals

  3)Decomposition of organic matter in dead plants andanimals
• Soil Horizons

  • Distinct layers found within the soil column (A, B, and C)
• Rhizospheres - metabolic ‘hot spots’ found around roots, fecal pellets, patches of organic matter, and

  mucus secretions

  • Although may only be 10% of soil volume, make up 90% of total metabolic activity
• A horizon (topsoil) – composed mostly of plant and animal bodies that are being reduced by humification

  A-0 – litter/detritus; Bacteria and fungi work in association with microarthropods (shredders)

  A-1 – Humus

  A-2 – leached zone
• B horizon – mineral soil organic compounds have been converted to inorganic compounds

  • leached down from the A horizon
• C horizon – Unmodified parent material

  • original that is disintegrating
• colluvial deposits - transported by gravity

  alluvial deposits – water

  eolian deposit - wind