Earth’s Energy Budget of Solar Energy
Feb 17, 2016
Earth’s Energy Budget of Solar
Energy
Purpose• To understand how Earth is heated from it
major source the Sun.– Reflection, absorption, and scattering of the Sun’s
electromagnetic spectrum energy
http://www.sci.uidaho.edu/scripter/geog100/lect/02-energy-seasons-atmosphere/02-pt-1-solar-energy.htm
Part 1• What kinds of natural
substances on Earth reflect solar energy? – Reflect: Snow, Water, Clouds
• Data– Clouds vs. No Clouds in full
greenhouse and dark soil.• 30 units are reflected by
clouds• Where do the other 70
units go?
Part 2• Albedo: the percentage of solar
energy reflected back by a surface
• Which of the materials here (black soil, white sand, water) do you think are reflecting more radiation, and which are absorbing more?– Reflects: Water and white sand– Absorbs: Black soil and water
absorbs more, but takes longer.• 50 absorbed by ground• 20 absorbed by atmosphere and
clouds
• Data– Temperature in soil and water
Part 2 Continue• What happens to the solar energy
while it is in the natural materials?– Short wavelengths (that don’t get
absorbed by the atmosphere) make atoms vibrate (kinetic energy), which warms the ground.
– The atoms release the energy as heat (infrared radiation - IR).
• What happens to the energy after it is re-emitted from the ground as infrared radiation?– 12 units (longest waves) go into space
Part 3• Where does the rest of infrared
radiation(IR) go? – Greenhouse gasses
• H2Ov, CO2, Methane, Nitrous Oxide, and O3
– 8 units• Data• Greenhouse effect (Scattering)
– Energy is released as IR and then is constantly absorbed and released by greenhouse gases = heat
– Good thing– Greenhouse enhancement: adding to much
CO2
• What happens when the sun goes down?
Part 4
• Which material (water or soil) will release heat the fastest (and slowest)?– Soil will release it fast– Water absorbs more heat but releases it slowly
• Data– Water temperature air temperature vs. Soil air
temperature– Water temperature vs. soil temperature
Mountain and Valley Breezes• Valley Breeze (Day)– Valleys heat faster than
mountains = Warm air from valleys moves upslope.
• Mountain Breeze (Night)– Mountains cool faster
than valleys = cool air descend from mountains to valleys
Land and Sea breezes
• Sea Breezes (Day)– Water towards the land– Land heats up quicker
than water• Land Breezes(Night) – Land towards the Water– Land cools quicker than
water