Changes

Solar [[technologies]] are broadly characterized as either [http://en.wikipedia.org/wiki/Passive_solar passive solar] or [http://en.wikipedia.org/wiki/Active_solar active solar] depending on the way they capture, [[convert]] and [[distribute]] solar energy. Active solar [[techniques]] include the use of photovoltaic panels and [http://en.wikipedia.org/wiki/Solar_thermal_energy solar thermal collectors] to harness the [[energy]]. Passive solar techniques include [[orienting]] a building to the [[Sun]], selecting [[materials]] with favorable [http://en.wikipedia.org/wiki/Thermal_mass thermal mass] or [[light]] [http://nordan.daynal.org/wiki/images/Light_dispersion_conceptual.gif dispersing] properties, and [[designing]] spaces that [[naturally]] [[circulate]] air.

Solar [[technologies]] are broadly characterized as either [http://en.wikipedia.org/wiki/Passive_solar passive solar] or [http://en.wikipedia.org/wiki/Active_solar active solar] depending on the way they capture, [[convert]] and [[distribute]] solar energy. Active solar [[techniques]] include the use of photovoltaic panels and [http://en.wikipedia.org/wiki/Solar_thermal_energy solar thermal collectors] to harness the [[energy]]. Passive solar techniques include [[orienting]] a building to the [[Sun]], selecting [[materials]] with favorable [http://en.wikipedia.org/wiki/Thermal_mass thermal mass] or [[light]] [http://nordan.daynal.org/wiki/images/Light_dispersion_conceptual.gif dispersing] properties, and [[designing]] spaces that [[naturally]] [[circulate]] air.

==Energy from the Sun==

==Energy from the Sun==

The [[Earth]] receives 174 [http://en.wikipedia.org/wiki/Orders_of_magnitude_(power)#petawatt_.281015_watts.29 petawatts] (PW) of incoming solar [[radiation]] (insolation) at the upper [[atmosphere]].[1] Approximately 30% is [[reflected]] back to [[space]] while the rest is absorbed by clouds, [[oceans]] and land masses. The [[spectrum]] of solar light at the [[Earth]]'s [[surface]] is mostly spread across the [[visible]] and [http://en.wikipedia.org/wiki/Near-infrared near-infrared] ranges with a small part in the [http://en.wikipedia.org/wiki/Near-ultraviolet near-ultraviolet].

The [[Earth]] receives 174 [http://en.wikipedia.org/wiki/Orders_of_magnitude_(power)#petawatt_.281015_watts.29 petawatts] (PW) of incoming solar [[radiation]] (insolation) at the upper [[atmosphere]]. Approximately 30% is [[reflected]] back to [[space]] while the rest is absorbed by clouds, [[oceans]] and land masses. The [[spectrum]] of solar light at the [[Earth]]'s [[surface]] is mostly spread across the [[visible]] and [http://en.wikipedia.org/wiki/Near-infrared near-infrared] ranges with a small part in the [http://en.wikipedia.org/wiki/Near-ultraviolet near-ultraviolet].

[[Earth]]'s land [[surface]], [[oceans]] and [[atmosphere]] absorb solar radiation, and this raises their [[temperature]]. Warm air containing evaporated [[water]] from the [[oceans]] rises, causing [[atmospheric]] [[circulation]] or [http://en.wikipedia.org/wiki/Convection convection]. When the air reaches a high altitude, where the [[temperature]] is low, water vapor condenses into clouds, which rain onto the [[Earth]]'s [[surface]], completing the [http://en.wikipedia.org/wiki/Water_cycle water cycle]. The latent [[heat]] of water condensation amplifies convection, producing atmospheric [[phenomena]] such as [[wind]], [http://en.wikipedia.org/wiki/Cyclone cyclones] and [http://en.wikipedia.org/wiki/Anti-cyclone anti-cyclones]. Sunlight absorbed by the [[oceans]] and land masses keeps the [[surface]] at an [[average]] [[temperature]] of 14 °C.[4] By [http://en.wikipedia.org/wiki/Photosynthesis photosynthesis] green plants convert solar [[energy]] into [[chemical]] energy, which produces [[food]], wood and the biomass from which [http://en.wikipedia.org/wiki/Fossil_Fuels fossil fuels] are derived.

[[Earth]]'s land [[surface]], [[oceans]] and [[atmosphere]] absorb solar radiation, and this raises their [[temperature]]. Warm air containing evaporated [[water]] from the [[oceans]] rises, causing [[atmospheric]] [[circulation]] or [http://en.wikipedia.org/wiki/Convection convection]. When the air reaches a high altitude, where the [[temperature]] is low, water vapor condenses into clouds, which rain onto the [[Earth]]'s [[surface]], completing the [http://en.wikipedia.org/wiki/Water_cycle water cycle]. The latent [[heat]] of water condensation amplifies convection, producing atmospheric [[phenomena]] such as [[wind]], [http://en.wikipedia.org/wiki/Cyclone cyclones] and [http://en.wikipedia.org/wiki/Anti-cyclone anti-cyclones]. Sunlight absorbed by the [[oceans]] and land masses keeps the [[surface]] at an [[average]] [[temperature]] of 14 °C.[4] By [http://en.wikipedia.org/wiki/Photosynthesis photosynthesis] green plants convert solar [[energy]] into [[chemical]] energy, which produces [[food]], wood and the biomass from which [http://en.wikipedia.org/wiki/Fossil_Fuels fossil fuels] are derived.