| Quick Links Title | Introduction | Electromagnetic Radiation | Photons Traveling to Earth | Photoelectric Effect | Sources |
| Photons Traveling to
Earth To the Earth's Atmosphere A photon is an elementary particle that is composed of electromagnetic energy. Because photons do not require a medium in order to travel they can be treated as particles traveling in a stream; photons oscillate at frequencies of 3 Hz up to 300 EHz (300 quintillion hertz) which allow them to be treated as wave also. Photons leave the Sun's atmosphere traveling in a straight line with the frequencies and wavelengths corresponding to a point on the electromagnetic spectrum. When photons are traveling from the Sun's atmosphere to the Earth's atmosphere they are said to be in space. When in space photons travel generally without restraint and reach the universal speed limit, c, the speed of light which is  meters per second or 671 million
miles per hour. Photons traveling at the speed of
light can be explained by Newton's first law of
motion which states that an object's velocity will
remain constant unless acted upon by a force.
Photons exit the Sun's atmosphere with the force
of energy pushing them outward, unless the photons
are acted upon by another force, their speed and
direction will remain constant. The photons
approach the Earth's atmosphere at the speed of
light, but once they come in contact with the
Earth's atmosphere they begin to interact with gas
molecules. The photons' interactions with gas
molecules is similar to the interactions they see
in the Sun's radiative zone. Gas molecules absorb
the photons and then instantly re-emit them. When
the photons are re-emitted they are sent about the
inside of the Earth's atmosphere in random
directions, although the majority of them fly
toward Earth's surface.
Solar Power Potential
Potential can be calculated for the amount of solar power available at the Earth's surface through some physics analysis and math. The solar constant, which is the amount of electromagnetic radiation seen at the distance of the Earth is a measure of flux density. By using the solar constant, a rough estimation of the potential solar power on Earth can be calculated, however this is just a basic outline which does not include adverse weather or atmospheric conditions that may inhibit the flow of electrons to Earth's surface. When photons from the Sun interact with the Earth's atmosphere there is a significant loss in the number of photons that enter Earth's atmosphere. Most of the loss is from Earth's atmosphere blocking the UV rays, some UV rays do make it through however. It is not possible to calculate the exact loss of photons, but a close estimate is attainable. There are multiple opinions where atmospheric loss is concerned, so in this page we will use 50% loss/retained as an example; that will cover 30% scattered on the way to the surface and 20% absorbed by the atmosphere and clouds (including UV blocking). Below is the detailed process for determining a value for the power potential from the Sun that the Earth sees.  The above table shows the
calculations for determining the potential
power at the Earth's surface in one day. To
get more precise, for instance, if the power
for land was wanted the final number in the
table would be multiplied by the ratio of land
or if time was wanted then the amount of time
could be factored in.
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