Solar Radiation

1. Explain in terms of the
   electromagnetic spectrum we have studied
   [remind yourself here] what are the types and
   amounts [descriptions are sufficient] of light produced by our star. State the other [only two] sources of energy
   input on Earth.
   
2. State and explain how
   the solar radiation that strikes Earth is distributed [see here]. Be sure to
   explain the concept of albedo and insolation.
   
   
3. Explain how
   the tilt of the Earth causes seasonal changes on Earth. Be sure to discuss the
   angle of sunlight with respect to latitude, not distances. Explain the seasonal effects on length of day,
   growing seasons changes in average temperature.
   
4. Identify a satellite responsible for gathering
   evidence about solar radiation flux. Describe its age, orbit and what it
   measures.
   

Three atmospheric processes modify the solar
radiation passing through our atmosphere destined to the Earth's surface. These
processes act on the radiation when it interacts with gases and suspended
particles found in the atmosphere. The process of scattering occurs when small
particles and gas molecules diffuse part of
the incoming solar radiation in random directions without any alteration to the
wavelength of the electromagnetic energy (Figure 7f-1). Scattering does,
however, reduce the amount of incoming radiation reaching the Earth's surface. A
significant proportion of scattered shortwave solar radiation is redirected back
to space. The amount of scattering that takes place is dependent on two factors:
wavelength of the incoming radiation and the size of the scattering particle or
gas molecule. In the Earth's atmosphere, the presence of a large number of
particles with a size of about 0.5 microns results in shorter wavelengths being
preferentially scattered. This factor also causes our sky to look blue because
this color corresponds to those wavelengths that are best diffused. If
scattering did not occur in our atmosphere the daylight sky would be
black.

Solar radiation is becoming increasingly appreciated because of its influence
on living matter and the feasibility of its application for useful purposes. It
is a perpetual source of natural energy that, along with other forms of
renewable energy, has a great potential for a wide variety of applications
because it is abundant and accessible. Solar radiation is rapidly gaining ground
as a supplement to the nonrenewable sources of energy, which have a finite
supply.

The solar radiation spectrum

Solar radiation is commonly divided into various regions or bands on the
basis of wavelength (Table 1). Ultraviolet radiation is that part of the
electromagnetic spectrum between 100 and 400 nm. It is, in turn, divided rather
arbitrarily from the viewpoint of its biological effects into three major
components (Fig. 1). Table 1. Spectral bands of incoming solar energy and
atmospheric effects.